POP3 (Post Office Protocol 3) is a protocol that provides a simple, standardized way for users to access mailboxes and download messages to their computers. One of the most used mail-protocols on the Internet.
Currently, POP3 (POP version 3) is the latest version. POP is a protocol for receiving email from a remote host in a single batch; it is best suited for non-interactive mail retrieval, where email is finally stored on the client computer. A competing protocol is imap.
The POP3 protocol runs on TCP port 110.