A server is a specialized computer that controls some resource. For example, a file server controls a set of files and determines who can access which files. Servers are usually installed in a server rack. A server rack is a row held within a server cabinet. A server cabinet may hold many different types of computer equipment. For example, a single cabinet may hold a file server, a web server, a database server, a networking bridge, and a backup file server. All of these devices fit inside their own racks. They can be easily interconnected, since all of their ports sit relatively close to each other. A server rack can also be used to house multiple fans, providing cooling to server equipment. Computer equipment gets very hot, and without adequate cooling, hardware can fail. Fans can help deliver cool air to particularly hot servers, keeping them from succumbing to heat damage.