IMAP (Internet Message Access Protocol) and POP (Post Office Protocol) are the protocols with which you can download messages from mail servers on your computer and access them with the help of mail clients such as Microsoft Outlook, Mozilla Thunderbird etc.
IMAP and POP are two different protocols. The main difference between them is that IMAP always syncs with mail server so that any changes you make in your mail client (Microsoft Outlook, Thunderbird) will instantly appear on your webmail inbox. On the other hand, in POP, your mail client account and mail server are not synced. It means whatever changes you make to your email account in the mail client will not be transferred to the webmail inbox.
In simple terms, if you are using IMAP and mark a mail as read, it gets marked as read in your web based inbox too because the changes are happening on the server. However, this won’t be the case if you are using POP, because the mails are downloaded to your PC so the changes won’t reflect on the server.
The biggest advantage of using IMAP is you can access your mail from multiple mail clients and each client detects the change in real-time. Suppose mail server is connected with two different mail clients (let’s say Client 1 and Client 2) on different computers. If the user deletes a message in mail client 1, the change will appear on mail server immediately and also on mail client 2. In IMAP all messages from mail clients and servers are synced with each other.
You can download emails from mail server to your PC using POP. After downloading, the original mail is removed from the server and hence you can’t access it from another computer. Or for instance, if you send a message from a mail client then you won’t find that message under sent items in your mailbox on another client.
So which is better IMAP or POP? In my opinion, it would be IMAP because it offers two way connection. Changes are synchronized to the server and you don’t have to worry about taking your mail client with you everywhere. However, if you are someone who hardly checks mail on any other computer then you could make use of POP too.