This is a question often asked. I need to start using Outlook Express to check my GMail, but what should I use - Pop3 or Imap?
Before we get into the comparison of both, lets look at them individually.
IMAP - IMAP stands for Internet Message Access Protocol. It is a protocol for accessing email from your local computer. It is a client/server protocol in which e-mail is received and held for you on the servers. You can view just the header information, which includes the sender and subject of the letter, allowing you to decide whether to download the message or not.
POP3 - POP3 stands for Post Office Protocol 3. It can act as a standard protocol to receive email on your client, or as a client/server protocol. The mail is stored on the server, until you download it on your client. Once downloaded the mail gets deleted from the server.
Coming to the main question. What is the difference between the two, and which is better?
No matter what the difference is, ultimately both of them solve the purpose of you checking your email in an email client, but often you will find that one suits you more than the other.
With IMAP, you have the liberty to download only the header of the emails, thus deciding which emails should be downloaded to your physical machine, whereas in POP3, you do not control the mails to be downloaded. By default, it downloads all the new mails received on the particular account.
Your mail remains on the server in case of IMAP, thus allowing you to check your emails from anywhere, whereas in case of POP3, once you download your mails, they get deleted from the server, so there are no longer accessible to you from the Internet.
One of the advantages of POP3 account is that you virtually get unlimited space, because your emails are downloaded on your machine, and your Inbox remains empty.
I leave to you which protocol you prefer to read your emails.