The barriers to entry in IT are lower than most people think. A commitment to learning, self-growth and finding a job that lets you capitalize on your innate strengths are some of the most important factors involved in switching careers into IT.

5 Most Popular Operating Systems

You’ve probably been involved in a “PC versus Mac” argument at some point in your life. Everyone seems to have very strong opinions on the subject, but what it really comes down to is personal preference in operating systems.
Most people know that they like one or another but may not be able to pinpoint what they really prefer about them. They may say they like a particular command prompt, or they enjoy some pre-installed software, the look and feel of the hardware, the applications or systems they can download, or even the pre-installed web browser. But the reality is that the features of an OS aren’t immediately clear to most users. A resource to help users understand the different processing and interaction elements of their favorite OS helps it become easier to work with.
Students (particularly online students), freelancers, contractors, and anyone who owns a phone, computer, or tablet should learn about different OSs so they can pick a computer and OS that meet their needs. If you’re planning to study IT in school and pursue an IT career, you’ll want a strong knowledge of OSs to make sure you’re prepared for all the skills you’ll need to be successful in your field.
What Is the Purpose of an Operating System?
- Booting: Booting is the process of turning on the computer and powering up the system.
- Memory management: This feature controls and coordinates the computer applications while allocating space for programs.
- Loading and execution: Your OS will load, or start up, a program and then execute the program so that it opens and runs.
- Data security: A good OS includes features that keep your data safe and computer programs secure. Security features are set up to keep unwanted cyberattackers at bay.
- Disk management: This manages all the drives installed in a computer, including hard drives, optical disk drives, and flash drives. Disk management can also be used to divide disks, format drives, and more.
- Process management: Your OS is designed to allocate resources to different computer processes, enable the processes to share information, protect them, and synchronize them.
- Device controlling: Your OS will allow you to open or block access to devices like removable devices, CD/DVDs, data transfer devices, USBs, and more.
- Printing controlling: As an extension of device controlling, your OS takes control of the printers that are connected to the computer, and the materials that need to be printed.
- User interface: Also referred to as a UI, this is the part of the OS that allows a user to enter and receive information. This can be done with typed commands, code, and other formats.

The Five Most Popular Operating Systems
There are five main types of operating systems. These five OS types are likely what run your phone, computer, or other mobile devices like a tablet. Whether you’re just a normal computer and phone user or someone hoping to get involved in an IT career, knowledge of applications and systems types will help you maintain security and user access, perform routine operations, and much more.
Microsoft Windows.
The Windows OS has been around since the 1980s and has had several versions and updates (including Windows 95, Windows Vista, Windows 7/8/10, etc.) Microsoft Windows is one of the popular operating system types and is preloaded on most new PC hardware. With each new Windows update or release, Microsoft continues to work on improving their users’ experience, hardware, and software, making Windows more accessible and easier to use.
Microsoft Windows contains a control panel, a desktop and desktop assistant, disk cleanup, event viewer, and more. Many users prefer Microsoft Windows because they say it’s compatible with many other kinds of software. Many kinds of computer programs run best on Microsoft Windows because they’re developed by Microsoft.
Apple macOS.
Head-to-head in the competition with Microsoft Windows is Apple’s macOS. macOS and Windows are both examples of proprietary operating systems, meaning that the company conceptualized, designed, developed, and now sells their own OS. They’re designed and sold by the companies and aren’t meant to be tampered with or tweaked by users. Apple and Macintosh computers run on the proprietary macOS and OS X system, the first of which launched 20 years ago. There are also previous versions or updates which include:
The macOS and Apple/Mac products are also known and beloved by their users for ease of use and continually improving user experience. Fast processing speeds, a simple desktop interface, and a wide variety of helpful resources make users excited about macOS. Many users relish the instant connection with their computers and mobile phone hardware, and enjoy the lack of bugs and hackers that Apple systems are known for.
Operating System Defined
To define the term operating system, let’s think in terms of stacks – one of the most common models used to describe computer systems. From network operations to software applications to emerging technology, solutions usually have multiple pieces that build on each other. Operating systems are no different.

The hardware is the foundation of any computing device – the physical pieces such as processors, memory or input/output ports. Direct access and control of this hardware is not user friendly because it only understands certain commands, and these commands are directly tied to the function of the hardware in a way that many people do not understand.
This is where an operating system comes in. The OS acts as a translation layer, creating user-friendly options, like a graphical user interface (GUI) with point-and-click capability, that are mapped to the hardware command language.
Of course, having access to the hardware is still not very useful for the average user. That access alone does not allow people to write documents, view pictures or surf the internet. For those actions, system software applications are needed. The most common way that an OS is used is as a platform for software developers, who use the translation capabilities to build application programs for end users
What Is an Operating System Kernel?
The stack model can also be applied to the operating system itself. The primary piece that performs translation for the hardware is known as the kernel. Given the costs involved with developing both hardware and software, there are clearly constraints around building new kernels, and the dynamics between hardware components and OS kernels have defined much of the current IT industry. This will be explored more in the section on different operating systems.

- Software libraries that are unique to a given OS
- The application programming interface (API) that allows developers to build applications
- The user interface (UI) that makes a device accessible to everyone, regardless of technical expertise
What Is Firmware?
Firmware is a specialized example of an operating system. The most popular operating systems are designed to be flexible. They can be used on many different devices, and they can act as a platform for many types of applications. Firmware is a much more focused device driver. Rather than providing openness, firmware is directly tied to specific hardware and provides a limited set of functions.
The reason that firmware is used rather than a more open operating system is performance. By focusing specifically on the exact hardware used and by limiting the functionality, developers can improve real-time performance and efficiency, or they can deliver a specific level of performance at a reasonable cost. This is important in situations where performance is critical or the functionality is already limited and cost becomes a major factor. Firmware is found in many single-purpose devices, such as printers and smart devices used in the internet of things.
Firmware vs. Software
Technically, the term software is very broad, covering any product written in a programming language that runs on computing hardware. In most cases, people use the term software when referring to applications that help with multitasking, such as spreadsheets, photo editing or video games.
However, operating systems and firmware are both examples of software as well. Since they usually come pre-installed and are tied so tightly to the basic operation of a device, they are more transparent for most users. However, operating systems are a type of software, and firmware is a type of operating system.

What Does an Operating System Do?
First, the OS manages the hardware on the device. This may include a central processing unit (CPU), a graphics processing unit (GPU), memory (including RAM and hard drives) and input/output (including keyboard, monitor, USB ports, etc.). All of these components perform different functions, and they usually come from a variety of suppliers. Tying it all together and making it work cohesively is the first job of the OS.
Second, an OS provides access for other developers to build software. For general purpose systems – such as personal computers and mobile devices – people want to perform a wide variety of tasks. Software developers can utilize the API provided by an operating system to build out the functionality of their program. Of course, different kernels use different APIs, so developers who want their software on multiple platforms have to build multiple versions.
Finally, an OS makes the device usable. Some operating systems only have a command-line interface, and users must have specific expertise to understand which commands to use. Other operating systems have a GUI, making the operation of the device much more accessible. Over the past decade, the types of UI have evolved to include touchscreens, gestures and voice commands.
What Types of Operating Systems Are There?
Common Desktop Operating Systems
Windows: Microsoft’s desktop OS is possibly the most important piece of software in tech history. In the 1980s, Microsoft developed a partnership with Intel, and the combination of the Windows operating system with Intel processors (known as the Wintel platform) took the world by storm.
Microsoft Windows became the OS used by a majority of people as the PC reached mass adoption – in January 2010, Windows was on 92% of all computing devices worldwide. Today, Windows is still a critical fixture, especially in business, where both Windows laptops and servers are well entrenched.
macOS: Historically, Apple’s desktops and laptops have not enjoyed the same market presence as Windows machines, but the original MacIntosh operating system introduced several GUI concepts that were later featured in Windows. As Apple became dominant in the mobile space, its Mac platform grew as well, with the OS evolving into OS X and now the current iteration as macOS.
Linux: Linux is … complicated. The history of Linux starts with the UNIX OS, released in 1971 by AT&T’s Bell Labs and made popular through the 1970s thanks to portability to different computing platforms and the antitrust requirement for AT&T to freely provide licenses when asked. When Bell Labs made UNIX proprietary after being divested from AT&T, the GNU Project was started to create free UNIX-like software.
In 1991, the Linux kernel was developed and incorporated into the GNU project, leading to an explosion of operating systems based on the Linux kernel. While the term Linux is often used as a name for an OS, there are technically many versions of the Linux operating system (known as distributions). These distributions, such as Ubuntu or Red Hat Enterprise Linux, are found in a wide variety of computing devices, including IBM.
Chrome: Google’s Chrome OS, used primarily in Chromebook laptops, is one of the operating systems based on the Linux kernel. It uses the Chrome browser as the primary user interface, limiting the user’s ability to access applications outside of the browser. This transfers most of the computing complexity to the internet, driving down the cost of the devices. Thanks to the low cost and the high degree of control, this Chromebook operating system has become popular in the education vertical.
Common Mobile Operating Systems

Because Android is free and open source, it has been used by many device manufacturers and has become the most popular OS in the world. As of April 2020, Android has 39% market share, compared to 33% for Windows, 17% for iOS and 8% for macOS(Statcounter).
tablets. The Android operating system was originally developed by Google and is now developed and maintained by the Open Handset Alliance, which is sponsored by Google.
iOS: In contrast to Android, Apple’s iOS is proprietary and only found on its own devices. In 2019, Apple announced that iPads would run on a variant of iOS known as iPadOS, but both iPhones and iPads are still generally considered iOS devices.
Although Android has greater market share, iOS devices dominate the high end of the mobile market, making iOS more attractive to developers and giving iOS the appearance of relatively even standing with Android.
Operating Systems Used in Internet of Things (IoT) Devices
Most IoT devices have firmware rather than a full OS, since the device has limited functionality and greater constraints around performance, power consumption and cost. This firmware is often either proprietary or based on the Linux kernel.
In the cases where a device might have a more robust operating system, the OS is somewhat transparent. For example, Amazon’s Echo devices use Fire OS, Amazon’s proprietary OS based on the Linux kernel. However, most people don’t recognize Fire OS as part of the device, typically identifying more with the Alexa UI.
For IT professionals, understanding the basics behind operating systems and the different ways that they might appear on devices is a key part of providing support. As part of the standard technology stack, operating systems are the bridge between the user that has a job to do and the hardware resources that can get the job done.
IT support professionals, such as help desk technicians, interact with operating systems daily. CompTIA A+ covers the skills needed to install, manage and troubleshoot operating systems. Download the exam objectives for free to see the skills you need to work in IT support.
Resources:
https://www.wgu.edu/blog/5-most-popular-operating-systems1910.html
https://www.comptia.org/content/articles/what-is-an-operating-system
https://www.comptia.org/content/articles/what-is-an-operating-system
Operating systems
This loop processes the entire header data. We do not provide any sort of LTC_FAST optimizations, since headers are usually empty or very short. Every 16 bytes of header data, we encrypt the PAD to emulate CBC-MAC properly.

Modern Operating System
Modern operating systems provide a general-purpose mechanism for processing data larger than available main memory called virtual memory. Transparent to the program, swapping moves parts of the data back and forth from disk as needed. Usually, the virtual address space is divided into units calledpages; the corresponding equal-size units in physical memory are called page frames. A page table maps the virtual addresses on the page frames and keeps track of their status (loaded/absent). When a page fault occurs (i.e., a program tries to use an unmapped page), the CPU is interrupted; the operating system picks a rarely picked page frame and writes its contents back to the disk. It then fetches the referenced page into the page frame just freed, changes the map, and restarts the trapped instruction. In modern computers memory management is implemented on hardware with a page size commonly fixed at 4,096 bytes.
Various paging strategies have been explored that aim at minimizing page faults. Belady has shown that an optimal offline page exchange strategy deletes the page that will not be used for a long time. Unfortunately, the system, unlike possibly the application program itself, cannot know this in advance. Several different online algorithms for the paging problem have been proposed, such as last-in-first-out (LIFO), first-in-first-out (FIFO), least-recently-used (LRU), and least-frequently-used (LFU). Despite that Sleator and Tarjan proved that LRU is the best general online algorithm for the problem, we reduce the number of page faults by designing data structures that exhibit memory locality, such that successive operations tend to access nearby memory cells.
Sometimes it is even desirable to have explicit control of secondary memory manipulations. For example, fetching data structures larger than the system page size may require multiple disk operations. A file buffer can be regarded as a kind of software paging that mimics swapping on a coarser level of granularity. Generally, an application can outperform the operating system’s memory management because it is well informed to predict future memory access.
Particularly for search algorithms, system paging often becomes the major bottleneck. This problem has been experienced when applying A* to the domain of route planning. Moreover, A* does not respect memory locality at all; it explores nodes in the strict order of f-values, regardless of their neighborhood, and hence jumps back and forth in a spatially unrelated way.
Microsoft Windows Operating Systems for PCs
MS-DOS – Microsoft Disk Operating System
Originally developed by Microsoft for IBM, MS-DOS was the standard operating system for IBM-compatible personal computers. The initial versions of DOS were very simple and resembled another operating system called CP/M. Subsequent versions have become increasingly sophisticated as they incorporated features of minicomputer operating systems.
Windows 1.0

Introduced in 1985, Microsoft Windows 1.0 was named due to the computing boxes, or “windows” that represented a fundamental aspect of the operating system. Instead of typing MS-DOS commands, Windows 1.0 allowed users to point and click to access the windows.
Windows 2.0

Windows 3.0

Windows 3.0 was released in May, 1900 offering better icons, performance and advanced graphics with 16 colors designed for Intel 386 processors. This version was the first release that provided the standard “look and feel” of Microsoft Windows for many years to come. Windows 3.0 included Program Manager, File Manager, Print Manager and games like Hearts, Minesweeper, and Solitaire. Microsoft released Windows 3.1 in 1992.
Windows NT 3.1 – 4.0

Windows NT (New Technology) was a 32-bit operating system that supported preemptive multitasking. There are actually two versions of Windows NT: Windows NT Server, designed to act as a server in networks, and Windows NT Workstation for stand-alone or client workstations.
Windows 95

Windows 95 was a major upgrade to the Windows operating system. This OS was a significant advancement over its precursor, Windows 3.1. In addition to sporting a new user interface, Windows 95 also included a number of important internal improvements. Perhaps most important, it supported 32-bit applications, which meant that applications written specifically for this operating system would run much faster.
Although Windows 95 was able to run older Windows and DOS applications, it essentially removed DOS as the underlying platform. This resulted in the removal of many of the old DOS limitations, such as 640K of main memory and 8-character filenames. Other important features in this operating system were the ability to automatically detect and configure installed hardware (Plug-and-Play).
Windows 98

Windows 98 supported a number of new technologies, including FAT32, AGP, MMX, USB, DVD, and ACPI. Its most visible feature, though, was the Active Desktop, which integrated the Web browser (Internet Explorer) with the operating system. From the user’s point of view, there was no difference between accessing a document residing locally on the user’s hard disk or on a Web server halfway around the world.
Windows 2000

Often abbreviated as “W2K,” Windows 2000 was an operating system for business desktop and laptop systems to run software applications, connect to Internet and intranet sites, and access files, printers, and network resources. Microsoft released four versions of Windows 2000: Professional (for business desktop and laptop systems); Server (both a Web server and an office server); Advanced Server (for line-of-business applications); and Datacenter Server (for high-traffic computer networks).
Windows Millennium Edition (ME)

The Windows Millennium Edition, called “Windows Me” was an update to the Windows 98 core and included some features that would be part of the Windows 2000 operating system. This version also removed the “Boot in DOS” option.
Microsoft Operating Systems for Servers and Mobile Devices
Windows Server
Windows Server is a series of Microsoft server operating systems. Windows servers are more powerful versions of their desktop operating system counterparts and are designed to more efficiently handle corporate networking, internet/intranet hosting, databases, enterprise-scale messaging and similar functions. The Windows Server name made its debut with the release of Windows Server 2003 and continues with the current release, Windows Server 2022.
Windows CE (November 2006)
A version of the Windows operating system was designed for small devices such as personal digital assistants (PDAs) or Handheld PCs in the Microsoft vernacular). The Windows CE graphical user interface (GUI) was very similar to Windows 95 so devices running Windows CE were meant to be familiar to Windows 95 users.
Windows Home Server
Announced in January 2007, Windows Home Server (WHS) was a “consumer server” designed to use with multiple computers connected in the home. Home Server allowed users to share files such as digital photos and media files, and also automatically backed up home networked computers. Through Windows Media Connect, Windows Home Server shared any media located on your WHS with compatible devices.
Windows Mobile
The mobile operating system for smartphones and mobile devices from Microsoft was based on the Windows CE kernel and designed to look and operate similar to desktop versions of Microsoft Windows. Windows Mobile was largely been supplanted by Windows Phone 7, although Microsoft did release, in 2011, Windows Embedded Handheld 6.5, a mobile OS compatible with Windows Mobile 6.5 that was designed for enterprise mobile and handheld computing devices.
Windows Phone
Windows’ mobile operating system for smartphones and mobile devices served as the successor to Microsoft’s initial mobile OS platform system, Windows Mobile. Unlike Windows Mobile, Windows Phone 7 was targeted more to the consumer market than the enterprise market. “WinPhone7” replaced the more traditional Microsoft Windows OS look and feel with new “Metro” design system introduced in Windows 8.
Windows Phone 7 featured a multi-tab Internet Explorer Mobile Web browser that used a rendering engine based on Internet Explorer 9. It also included Microsoft Office Mobile, a version of Microsoft Office tailored for mobile devices. Its successors included Windows Phone 8 and Windows 10 Mobile. Microsoft announced the end of life for Windows Phone on January 14, 2020.
Webopedia’s Top 5 Study Guides
This article was last updated February 22, 2021 by Kaiti Norton.

What’s the Difference Between Firmware and an OS?

Many devices just run “firmware“—a type of low-level software that’s generally programmed directly into the memory of a hardware device. Firmware is usually just a small bit of software designed to do only the absolute basics.
When a modern computer boots up, it loads UEFI firmware from the motherboard. This firmware is low-level software that quickly initializes your computer’s hardware. It then boots your operating system from your computer’s solid-state drive or hard drive. (That solid-state drive or hard drive has its own internal firmware, which handles storing data on the physical sectors inside the drive.)
The line between firmware and an operating system can get a little blurry, too. For example, the operating system for Apple’s iPhones and iPads, named iOS, is often called a “firmware.” The PlayStation 4’s operating system is officially called a firmware, too.
These are operating systems that interface with multiple hardware devices, provide services to programs, and allocate resources among applications. However, a very basic firmware that runs on a TV remote control, for example, isn’t generally called an operating system.
The average person doesn’t need to understand exactly what an operating system is. It may be helpful to know what operating system you have to know which software and hardware your device is compatible with, however.

Chris Hoffman
Chris Hoffman is Editor-in-Chief of How-To Geek. He’s written about technology for over a decade and was a PCWorld columnist for two years. Chris has written for The New York Times and Reader’s Digest, been interviewed as a technology expert on TV stations like Miami’s NBC 6, and had his work covered by news outlets like the BBC. Since 2011, Chris has written over 2,000 articles that have been read nearly one billion times—and that’s just here at How-To Geek.
Read Full Bio »
Resources:
https://www.sciencedirect.com/topics/computer-science/modern-operating-system
https://www.webopedia.com/definitions/windows-operating-system-history/
https://www.howtogeek.com/361572/what-is-an-operating-system/
Operating systems
IBM no longer develops OS/2, but a company named Serenity Systems has the rights to continue distributing it. They call their operating system eComStation. It’s based on IBM’s OS/2 and adds additional applications, drivers, and other enhancements.

Modern Operating System
Modern operating systems provide a general-purpose mechanism for processing data larger than available main memory called virtual memory. Transparent to the program, swapping moves parts of the data back and forth from disk as needed. Usually, the virtual address space is divided into units calledpages; the corresponding equal-size units in physical memory are called page frames. A page table maps the virtual addresses on the page frames and keeps track of their status (loaded/absent). When a page fault occurs (i.e., a program tries to use an unmapped page), the CPU is interrupted; the operating system picks a rarely picked page frame and writes its contents back to the disk. It then fetches the referenced page into the page frame just freed, changes the map, and restarts the trapped instruction. In modern computers memory management is implemented on hardware with a page size commonly fixed at 4,096 bytes.
Various paging strategies have been explored that aim at minimizing page faults. Belady has shown that an optimal offline page exchange strategy deletes the page that will not be used for a long time. Unfortunately, the system, unlike possibly the application program itself, cannot know this in advance. Several different online algorithms for the paging problem have been proposed, such as last-in-first-out (LIFO), first-in-first-out (FIFO), least-recently-used (LRU), and least-frequently-used (LFU). Despite that Sleator and Tarjan proved that LRU is the best general online algorithm for the problem, we reduce the number of page faults by designing data structures that exhibit memory locality, such that successive operations tend to access nearby memory cells.
Sometimes it is even desirable to have explicit control of secondary memory manipulations. For example, fetching data structures larger than the system page size may require multiple disk operations. A file buffer can be regarded as a kind of software paging that mimics swapping on a coarser level of granularity. Generally, an application can outperform the operating system’s memory management because it is well informed to predict future memory access.
Particularly for search algorithms, system paging often becomes the major bottleneck. This problem has been experienced when applying A* to the domain of route planning. Moreover, A* does not respect memory locality at all; it explores nodes in the strict order of f-values, regardless of their neighborhood, and hence jumps back and forth in a spatially unrelated way.
Data Management
Memory management
Modern operating systems provide the abstraction of virtual memory to user processes ( Peter Denning—Virtual Memory, 1970 ). Virtual memory hides the true storage medium and makes data byte addressable regardless of where it actually resides. Operating systems provide each process a separate virtual memory address space, allowing them to execute with the entire virtual address space at their disposal. The most important aspect of virtual memory for this discussion is that it allows a process to execute without the need to have all of its code and data resident in the CPU main memory (i.e., DRAM).
The virtual address space of a process is divided into fixed-size blocks, called pages. In the physical memory system, the physical address space (the range of actual memory locations) is likewise divided into equally sized frames so that a frame is capable of storing a page. Virtual pages can be mapped to any frame in main memory, mapped to a location on disk, or not yet be allocated. However, the CPU requires a page to be in a main memory frame when it is being accessed or executed. When a process executes an instruction using a virtual memory address, a hardware unit called the Memory Management Unit (MMU) intervenes and provides the mapping of the virtual address to the physical address. If the physical address of a page is not in main memory, a page fault occurs, and the process is suspended while the page is retrieved and a virtual-to-physical mapping is created. This technique is known as demand paging and is completely transparent to the user process (except for the time it takes to service the page fault). Figure 7.1 shows an example of demand paging.

Virtual memory has implications on data transfer performance in OpenCL, since transferring data from the CPU to the GPU when using a discrete GPU uses Direct Memory Access (DMA) over the PCI-Express bus. DMA is an efficient way to access data directly from a peripheral device without CPU intervention. DMA requires that the data is resident in main memory and will not be moved by the operating system. When the operating system does not have the discretion to move a page, the page is said to be pinned (or page-locked).
The PCI-Express protocol allows any device connected to the bus, such as a GPU, to transfer data to or from the CPU’s main memory. When performing DMA transfers, a device driver running on the CPU supplies a physical address, and the DMA engine on the GPU can then perform the transfer and signal to the CPU when it has completed. Once the transfer completes, the pages can then be unmapped from memory.
Modern x86 systems use an I/O Memory Management Unit (IOMMU) as an interface between the PCI-Express bus and the main memory bus ( AMD IOMMU Architectural Specification; Intel Virtualization Technology for Directed I/O Architecture Specification ). The IOMMU performs the same role for peripheral devices as the MMU does for x86 cores, mapping virtual I/O addresses to physical addresses. The major benefit of utilizing an IOMMU for a GPU is that it allows the device to perform DMA transfers from noncontiguous physical address locations and allows access to physical locations that may be out of the range of addresses supported by the device. A block diagram of system with an IOMMU is shown in Figure 7.2 .

Boot images
A boot image in Configuration Manager is a Windows PE (WinPE) image that is used during an operating system deployment. Boot images are used to start a computer in WinPE, which is a minimal operating system with limited components and services that prepare the destination computer for Windows installation. Configuration Manager provides two boot images: One to support x86 platforms and one to support x64 platforms. These are considered default boot images. Boot images that you create and add to Configuration Manager are considered custom images. Default boot images can be automatically replaced when you update Configuration Manager. For more information about boot images, see Manage boot images.
Operating system images in Configuration Manager are stored in the Windows Imaging (WIM) file format and represent a compressed collection of reference files and folders that are required to successfully install and configure an operating system on a computer. For all operating system deployment scenarios, you must select an operating system image. You can use the default operating system image or build the operating system image from a reference computer that you configure. For more information, see Manage operating system images.
Linux, FreeBSD, and More
No list of alternative PC operating systems could be complete without Linux. It’s the alternative PC operating system. Linux comes in many different flavors, known as Linux distributions. Ubuntu and Mint are some of the most popular. If you want to install a non-Windows operating system on your PC and actually use it, you should probably pick Linux.
Linux is a Unix-like operating system, and there are other open-source operating systems like FreeBSD out there. FreeBSD uses a different kernel, but it uses much of the same software you’d find on a typical Linux distributions. The experience of using FreeBSD on a desktop PC will be pretty similar.

SkyOS
Unlike many of the other hobbyist operating systems here, SkyOS is proprietary and not open-source. You originally had to pay for access so you could use development versions of SkyOS on your own PC. Development on SkyOS ended in 2009, but the last beta version was made available as a free download in 2013.


Chris Hoffman
Chris Hoffman is Editor-in-Chief of How-To Geek. He’s written about technology for over a decade and was a PCWorld columnist for two years. Chris has written for The New York Times and Reader’s Digest, been interviewed as a technology expert on TV stations like Miami’s NBC 6, and had his work covered by news outlets like the BBC. Since 2011, Chris has written over 2,000 articles that have been read nearly one billion times—and that’s just here at How-To Geek.
Read Full Bio »
Resources:
https://www.sciencedirect.com/topics/computer-science/modern-operating-system
https://docs.microsoft.com/en-us/mem/configmgr/osd/understand/introduction-to-operating-system-deployment
https://www.howtogeek.com/190217/10-alternative-pc-operating-systems-you-can-install/