According to Top500, a site that maintains statistics on the worlds top supercomputers, 185 of the top 500 were built by IBM and 209 were built by HP. 277 of the top 500 supercomputers are in the United States. 446 of the top 500 supercomputers are running the Linux operating system.

Linux is freely-distributable open source operating system that runs on a number of hardware platforms. The Linux kernel was developed mainly by Linus Torvalds. Because it's free, and because it runs on many platforms, including PCs and Macintoshes, Linux has become an extremely popular alternative to proprietary operating systems.

• Low cost: You don't need to spend time and money to obtain licenses since Linux and much of it's software come with the GNU General Public License. You can start to work immediately without worrying that your software may stop working anytime because the free trial version expires.
• Stability: Linux doesn't need to be rebooted periodically to maintain performance levels. It doesn't freeze up or slow down over time due to memory leaks and such. Continuous up-times of hundreds of days (up to a year or more) are not uncommon.
• Performance: Linux provides persistent high performance on workstations and on networks. It can handle unusually large numbers of users simultaneously.
• Network friendliness: Linux was developed by a group of programmers over the Internet and has therefore strong support for network functionality; client and server systems can be easily set up on any computer running Linux. It can perform tasks such as network backups faster and more reliably than alternative systems.
• Flexibility: Linux can be used for high performance server applications, desktop applications, and embedded systems. You can save disk space by only installing the components needed for a particular use. You can restrict the use of specific computers by installing for example only selected office applications instead of the whole suite.
• Compatibility: It runs all common Unix software packages and can process all common file formats.
• Choice: The large number of Linux distributions gives you a choice. Each distribution is developed and supported by a different organization. You can pick the one you like best; the core functionalities are the same; most software runs on most distributions.
• Fast and easy installation: Most Linux distributions come with user-friendly installation and setup programs.
• Full use of hard disk: Linux continues work well even when the hard disk is almost full.
• Multitasking: Linux is designed to do many things at the same time; e.g., a large printing job in the background won't slow down your other work.
• Security: Linux is one of the most secure operating systems. "Walls" and flexible file access permission systems prevent access by unwanted visitors or viruses.
• Open source: If you develop software that requires knowledge or modification of the operating system code, Linux's source code is at your fingertips.

Today, the combination of inexpensive computers and free high-quality Linux operating system and software provide incredibly low-cost solutions for both basic home office use and high-performance business and science applications. The available choices of Linux distributions and Linux software may be overwhelming at first, but it if you know where to look, it shouldn't take long for you to find good online guidance.