IMAP is short for Internet Message Access Protocol, and it’s a popular alternative POP3. That’s another message protocol. IMAP differs from POP3 because it keeps all your emails on their server until you decide to delete them. It’s generally considered to be better for accessing your emails online. They are only saved to your computer if you decide to download them. You can choose which protocol you prefer and whether or not to download your emails when you’re setting up your email client.
IMAP lets you get at your emails from anywhere, so long as you have an Internet connection. Your emails live on the mail server, so they are effectively backed up and safer than if you keep them yourself. Of course, the downside is that you do need a reliable connection, so, if you live somewhere remote then you might want to take that into account. IMAP can give simultaneous mailbox access to multiple users and it comes with additional options for email management functions like search, email state information, multiple mailboxes, shared folders etc.