POP stands for Post Office Protocol, and is one of the technologies used for that all-important medium of communication: email. Like many other computer-related things, email requires a special language for mail to be received or sent. POP is one of the technologies that allows email sent from anywhere in the world to arrive in your inbox.

When a person sends an email to your address, it is transmitted over the Internet, and eventually lands on your email server. In order for your personal computer to get that mail it must follow a certain protocol. POP allows your computer to talk to the email server and then download all of the messages each time you connect.

One of the advantages of POP is the ability to download all of your messages onto a local computer. This way, you can view your messages on the go, without having a live Internet connection. Before a flight, a user could access all of his email and then view them via laptop in the plane when an Internet connection may be limited or unavailable.

The other benefit of POP is for email servers with limited storage space. For example, a small company may have only one small email server for its entire staff. If each person periodically downloads all of his or her email to a local computer, it saves the company from having to invest in more storage space.

Of course, there are always downsides, and POP is no exception. Post Office Protocol is not the ideal choice for the increasingly mobile population with more than one computer. Once the email is downloaded off the email server, it resides permanently on the local computer unless it's sent somewhere else. So an office worker accessing email in the office will not be able to then view email again at home, since all email will be stored on the office machine. Other solutions that address this concern include IMAP and Microsoft Exchange Server email accounts. These technologies allow all email to be read directly from a server, so all emails are readily available no matter what computer the user is using. The downside to this is that if there is an Internet access disruption, then there will be no accessing email at all.