Nonproprietary
In 1991 Linus Torvalds of Finland began asking for volunteer programmers over the Internet to collaborate on the development of a UNIX-like OS for personal computer s; the "1.0" release of Linux was in 1994. A true multiuser, multitasking system, Linux contained features (e.g., virtual memory, shared libraries, memory management, and {{link=TCP/IP">TCP/IP networking) formerly only found on mainframe computers. With its source code freely available, thousands of volunteers, as well as several companies that sell prepackaged Linux products, have contributed to the OS. A reliable, fast-performing system with good security features, Linux is popular for corporate computer network and Web server s.