A server is a computer that’s configured to efficiently take network requests, process them, and send network responses. You can use any general purpose computer as a server, but custom built computers will likely be more efficient.

Servers can be self-hosted, co-located by high speed internet connections, or part of server “farms” where a lot of computers and hard drives are stored in dedicated racks where a physical hard drive failure means they pull out that drive and pop in a new one, with no loss of data because the data is written to multiple disks.