自由／开源软件表面上是一个新的概念，但其实在因特网出现之前很久就已存在。自由／开源软件已经证明能够胜任高负荷的关键应用。有些自由／开源软件是使因特网成为可能的支柱。以下是几个成功的自由／开源软件项目。
BIND （域名服务器）
如果没有域名服务器（Domain Name Servers, DNS）的话像 yahoo.com 和 microsoft.com 这样的地址就不能使用。这些服务器把容易让人理解的域名和计算机能够识别的数字信息相互转换。没有这些服务器，用户就得强记像 202.187.94.12 这样的数字才能访问网站。
伯克利因特网名称域（Berkeley Internet Name Domain, BIND）服务运行在95％的域名服务器上[82]，包括大部分的 DNS 根服务器。这些服务器保存着因特网上所有域名的主记录。BIND 是因特网软件联盟（Internet Software Consortium）在 BSD 授权方式下发布的自由／开源软件。
Apache （网页服务器）
负责接受和响应浏览器发送的请求的 Apache 网页服务器是今天万维网（World Wide Web, WWW）的基础。从1996年4月起，Apache 就是使用最多的网页服务器，目前占有62.53％的网页服务器市场[83]。这个份额比其最接近的竞争对手，微软的 IIS 服务器市场份额（27.17％）的两倍还要多。
这些数据每月都有波动。最新的数据可以从 Netcraft 的网页服务器调查网站获得，网址是：http://news.netcraft.com/archives/web_server_survey.html。
Sendmail （电子邮件服务器）
没有电子邮件，我们今天的因特网不会存在。自由／开源软件在这方面有一次成了主要的推动因素。邮件服务器（有时被称为邮件传送程序，Mail Transport Agent 或 MTA）的功能是把用户的电子邮件传送到目的地。像邮件转发和重定向，垃圾邮件拒收和中转这样的功能增加了邮件服务器的复杂程度。垃圾邮件（或称 spam）的问题使安全问题显得尤为重要，因为垃圾邮件发送者会夺取邮件服务器的控制权并影响一般用户的使用。
D. J. Bernstein 2001年的一项研究发现 Unix Sendmail 拥有最大的市场份额，占所有邮件服务器的42％。这比它的两个最大竞争者，占18％的微软 Exchange 和占17％的 Unix qmail 加起来还要多[84]。注意 qmail 是基于 Unix 的邮件服务器但授权条款限制性太强，并不是自由／开源软件。
OpenSSH （安全的网络管理工具）
当用户通过因特网连接到远程服务器时数据可能会经过多个子网络，因此安全成为一个主要问题。Secure Shell （SSH）协议允许系统管理员安全地远程管理服务器，因为他们传送的信息几乎不可能被截获和解码。
OpenSSH 是 SSH 协议的一个开源实现，其市场占有率从2000年的5％增长到2002年4月的66.8％。OpenSSH 的出现是当时限制性的标准 SSH 实现改变授权方式的结果。
Open Office （办公套件）
用于服务器的自由／开源软件已经相当强大，但自由／开源软件的桌面应用相对起步较晚。在过去私有的 StarOffice 代码基础上开发的 Open Office 是功能与微软 Office 相似的自由／开源软件，具有微软 Office 的大部分功能。它包括功能齐备的字处理软件、电子表格和演示软件。对于许多正在考虑从 Windows 桌面迁移到 Open Office 的用户来说，它的一个重要优点是能够顺利地读取微软 Office 生成的大部分文档。这一点方便了平台转换，因此 Open Office 在近期一些被广为宣传的从 Windows 向 Linux 迁移的计划中都被采用。虽然它目前并没有很大的市场份额，但随着更多的组织使用这个功能完整，价格低廉的软件，预计它将会有很大的发展。
While FOSS may seem a relatively new concept, it has actually been around since long before the Internet came into existence. FOSS has more than proven that it is ready for prime time, mission-critical usage. In some cases, it is the critical linchpin that makes the Internet possible. The following is a small sample of successful FOSS projects.
BIND (DNS Server)
Internet addresses such as yahoo.com or microsoft.com would not function if not for Domain Name Servers (DNS). These servers take these human-friendly names and convert them into the computer-friendly numeric addresses and vice-versa. Without these servers, users would have to memorize numbers such as 202.187.94.12 in order to use a website.
The Berkeley Internet Name Domain (BIND) server runs 95 percent of all DNS serversi, including most of the DNS root servers. These servers hold the master record of all domain names on the Internet. BIND is a FOSS program licensed under a BSD-style license by the Internet Software Consortium.
Apache (Web Server)
Responsible for receiving and fulfilling requests from web browsers, the Apache web server is one of the foundations of the World Wide Web (WWW) as we know it today. Apache has been the number one web server since April 1996 and currently commands 62.53 percent of the total web server marketii. That is more than double the market share (27.17 percent) of its closest competitor, Microsoft’s IIS server.
These figures fluctuate monthly of course. The latest figures can be found at Netcraft’s Web Server Survey site, at:
http://news.netcraft.com/archives/web_server_survey.html.
Sendmail (Email Server)
The Internet as we know it would not exist without email and once again, FOSS is one of the primary drivers. An email server’s (sometimes called a Mail Transport Agent or MTA) function is to deliver user email to its destination. Complex functionality, such as email forwarding and redirection, junk email rejection and routing, makes email servers rather complex systems. The problem of junk email (sometimes referred to as spam) makes security a critical feature, as spammers sending their unsolicited email to unsuspecting users would otherwise hijack an email server and render it useless to legitimate users.
A 2001 survey by D.J. Bernstein found that Unix Sendmail had the largest market share, at 42 percent of all email servers. This was larger than the share of its next two competitors combined, Microsoft Exchange and Unix qmail, with 18 percent and 17 percent, respectivelyiii. Note that qmail is a Unix-based email server but is not FOSS as its licensing terms are too restrictive.
OpenSSH (Secure Network Administration Tool)
Because Internet traffic can pass through multiple networks when a user connects into a remote server, security is a major concern. The Secure Shell (SSH) protocol allows system administrators to control their servers from a distance, safe in the knowledge that it is almost impossible to intercept and decipher the information that they may be transmitting.
OpenSSH, a FOSS implementation of the SSH protocol, has grown from a mere five percent of the market in 2000 to 66.8 percent of the market in April 2002. OpenSSH came into existence as a result of a restrictive licensing change in the standard SSH implementation at that time.
Open Office (Office Productivity Suite)
While FOSS products have been strong on the server side, FOSS desktop applications are relatively new. Open Office, which is based on the source code of the formerly proprietary StarOffice, is a FOSS equivalent of Microsoft Office, with most of its features. It includes a full-featured word processor, spreadsheet and presentation software. One of the advantages for many considering the shift from a Windows desktop environment to Open Office is that it reads most Microsoft Office documents without problems. This makes the transition relatively painless and Open Office has been used in recent high profile switches from Windows to Linux. While it does not have a very large market share as yet, its usage is expected to grow dramatically over time as more organizations use this full-featured, low-cost application.