POP3 protocol will download your emails to your local email program (e.g. Outlook, Mail, etc.) where IMAP will "connect" your email program directly to the server. IMAP keeps all mail on the server, allowing you to connect from other locations, perhaps by way of Webmail, while keeping your messages there. Connection times are very quick with IMAP. On first connection, IMAP downloads only the message headers versus a POP3 connection downloading your entire mail queue.
