What is the difference between POP3 and IMAP Mail Server?

IMAP:An Internet messaging protocol that enables a client to access mail on a server rather than downloading it to the computer. IMAP4 is designed for environments where users log on to the server from a number of different workstations, or log in remotely from outside of a firewall.This is independent of the machine which we uses. POP:An Internet protocol that allows messages to be downloaded from a server to the local computer. This is effective for systems that cannot maintain a continuous connection with the server. This is dependent to the machine which we uses.