Among the 36 legendary software projects in InfoWorld's Open Source Hall of Fame, these 10 top our list as the most important and valuable. It's a rare software product that has no alternatives, but the software landscape would be far poorer without any one of these nearly indispensable tools.\nRead the full story about all 36 hall of famers.\n#1. Linux kernel\nLinux wasn't the first open source software project, but it was the one that showed the world how powerful community development \u2014 on an Internet scale \u2014 could be. The product of thousands of project contributors, the stable, reliable, and malleable Linux kernel is the foundation of an enormous variety of operating system distributions.\n#2. GNU utilities and compilers\nThe GNU Project is the flagship of the free software movement and the source of an amazing variety of tools and utilities that, when combined with the Linux kernel, provide a complete operating system. With the Linux kernel, the GNU utilities and the GNU Compiler Collection make up the holy trinity of the Linux world.\n#3. Ubuntu\nThe first principle of Ubuntu is ease of use, making it the Linux distribution of choice for novice users and for sellers of PCs with Linux pre-installed. Derived from Debian GNU\/Linux, Ubuntu also benefits from Debian's excellent apt-get package management tool.\n#4. Three BSDs\nLinux isn't the only popular free open source operating system, or necessarily even the best. FreeBSD is famous for superior reliability and performance. NetBSD is celebrated for supporting a wide range of hardware platforms, including embedded systems and mobile devices. And spiny OpenBSD is touted as perhaps the most secure Unix-like operating system, with a security audit that never stops.\n#5. Samba\nSamba bridges the gaps between Linux\/Unix and Windows, allowing Linux and Unix servers to provide file and print services to Windows clients, and Linux and Unix clients to work with Windows file servers. A Samba host can even serve as the primary domain controller for a Windows network.\n#6. MySQL\nWhat's wrong with using a database you actually like? As the huge and active MySQL user community attests, nothing at all. MySQL's easy administration, excellent read performance, and transparent support for large text and binary objects make it the top choice for many Web sites.\n#7. BIND\nThe most popular DNS (Domain Name System) server since the dawn of the Internet, BIND (for Berkeley Internet Name Domain) helps to hide those ugly computer IP addresses so that we humans can use simpler names like gobears.com and infoworld.com.\n#8. Sendmail\nBorn before the Internet was standardized, flexible Sendmail served as the backbone of the Internet mail system throughout the 1980s and 1990s. It has lost ground to Postfix, Qmail, Exim, and Microsoft Exchange in recent years, but still ranks among the most popular MTAs (mail transfer agents).\n#9. OpenSSH and OpenSSL\nOpenSSH and OpenSSL bring indispensable tools for secure Internet communications to the world of free and open source. OpenSSH encrypts shell communications to remote computers, addressing the shortcomings in tools such as rlogin and telnet, which send usernames and passwords in clear text. OpenSSL is a software library that allows developers to incorporate SSL or TLS into their Internet applications.\n#10. Apache\nHalf of the world's Web sites (112 million and counting) can't be wrong. The Web server that put the A in LAMP is still fast, flexible, and secure, with broad operating system and Web programming language support and hundreds of modules available to extend the functionality.