What Server is
A host computer on a network. It houses information and responds to requests for information (for example, it houses Web sites and executes their links to other Web sites). The term "server" also refers to the software that makes the act of "serving information" possible. Commerce servers, for example, use software to run the main functions of an e-commerce Web site, such as product display, online ordering, and inventory management (you'll also hear this described as shopping cart technology). A server is the control computer on a LAN, meaning it controls the software, access to printers, and other parts of the network (usually accompanied by workstations that "share the load"). A server may be dedicated (where its sole purpose is to be the server) or non-dedicated (where in addition to being the server, it can be used for basic computing purposes).
The meaning of Anonymous FTP
An option in File Transfer Protocol (FTP) that allows you to connect to an FTP site, search through available files, and download any file, document, or program without having to establish an account (a username and password) on the system where the material resides. Most FTP servers allow a limited amount of anonymous FTP users to login at the same time and access only designated files.