Apache is one of the most popular and well-known web server software packages. It is not only available for free, it is also open source. This means that it can be modified and rebuilt to the user's specifications. Apache's primary function is to accept requests from remote users either on a local network or the Internet and respond to those requests with files from the machine on which it is running.

Apache can run on any number of operating systems. Apache is typically configured using a file with a name like "httpd.conf." This file contains numerous parameters including the port on which HTTP traffic will be served, which is 80 by default. Accessing an Apache-hosted site that is running on a different port will require that the URL be followed by a colon and the port number. For example, a server at FooBar.com on port 2051 would be accessed using this URL: http://www.foobar.com:2051

Apache is popular due to its stability, speed and universal design. Installing Apache is simple and requires little configuration to get a site up and running. On Windows-based servers, installation is simply a matter of running an installer EXE file. In Linux, a package manager such as "apt" can be used to accomplish the same thing. It is important to note that when choosing a version of Apache to download that you get the latest available one. Older versions might have security exploits that had not yet been patched. Since Apache has access to your computer's filesystem, it is important that you keep it up to date and secure.

If you so wish, you can administrate Apache remotely using an SSH shell. A highly useful feature is using a Unix system's "tail" command with the "-f" parameter to follow the access logs generated by Apache in real-time. This allows the webmaster to see what files are accessed and when.