What is POP3?
What exactly is POP3?
POP3 stands for Post Office Protocol version 3. It's one of the older ways a mail program fetches your mail. Its defining feature: messages are downloaded to the device you're working on, and by default removed from the server.
Explanation
The big difference with IMAP is synchronization. With POP3 your mail lives on a single device; if you read or delete something, your other devices notice nothing of it. That can be handy if you deliberately want to keep everything on one computer, but for most people with a laptop and a phone, IMAP is more practical. If you want to weigh the two up, read IMAP or POP: which to choose.
Example
On your office PC you fetch the mail for you@yourbusiness.com via POP3. The messages are now on that PC. If you later open your phone, you won't see them there. After all, they've already been downloaded to your office PC and removed from the server.
When do you choose POP3?
POP3 mainly makes sense if you deliberately work on one fixed device and want to keep your mail locally, for example on a PC that isn't always online. If you want to limit storage on the server, it can also help. For most self-employed people who work on a laptop and a phone, however, IMAP is more practical, because everything then stays synchronized everywhere.
Related terms
Torn between the two? IMAP or POP: which to choose helps you make the right choice in a few minutes.