IMAP is a more complex protocol that allows you to keep your mail on the remote server, in a collection of folders. Since the mail is stored on the server, you can access the same mail folders from different computers.
If you only use one computer, POP is probably best, because if you configure your e-mail program to remove messages from the server, you will lower the risk of missing messages from going over quota. If you would like to access the same messages from two different computers, like at home and at the office, IMAP makes things easier.
If you are running a laptop and wish to access your e-mail while offline, you can test out your e-mail client's "IMAP synchronization" capability. Since this can be tricky (buggy) for e-mail software to implement, downloading messages to a laptop via POP is the most reliable solution for offline access.
As always, we do also offer a Webmail client, should you be traveling and wish to check your email. You can reach it at https://east-mx.revion.com