Internet Message Access Protocol.  This is an e-mail protocol, used to access e-mail on a mail server and it is better than POP in the sense that with POP e-mail is downloaded from the server to your computer and removed from the server.  With IMAP the e-mail remains on the server and you can create folders on the server.  This means that if your computer breaks or gets stolen, your e-mail will be safe on the server and the folder structure will stay intact.  It can be considered a form of hosted e-mail.