IMAP (Internet Message Access Protocol) - definition
An Internet protocol used by email clients to access messages from a server. IMAP is a newer alternative to POP3.
Unlike POP3, which only downloads the messages, IMAP synchronizes them with the email server and tracks changes in their status. Another feature of IMAP is that it allows messages to be organized by folders and the email client setup to use IMAP access will also synchronize the folders beside the emails themselves.