IMAP, POP & SMTP

IMAP (Internet Mail Access Protocol) is better if you use multiple devices - each device syncs with the mail server, so you see the same emails on all devices. Email is stored on the server, with a copy synced to each device. This makes it much easier if you need to change your device - you simply connect the new email client up to the server and it'll automatically sync to the new client.

POP3 (Post Office Protocol) works by a client connecting to the server, retrieving email, and then (normally*) requesting the email be deleted from the server, there is no 'sync' as with IMAP. (* whether an email gets deleted from the server or not is controlled by the email client requesting it - if the client doesn't request deletion the email will stay on the server, no matter what happens to the email on the client (read/unread/deleted). Should your client not request deletion, when a new client is connected all the previous email will be delivered and appear unread. That email will also be taking up disk space in your account.)

We use SMTP (Simple Mail Transport Protocol) for sending an email - this is an internet standard.