Explain what POP means and what its essence is?

The term POP (Post Office Protocol) is an application layer protocol used to retrieve emails from a mail server to a client device.

The essence of POP is that the client connects to the server, downloads all new emails, and usually deletes them from the server (depending on settings). This allows working offline with mail, but emails are stored locally and not on the server.

Main features of POP:

• Simplicity and wide support.
• The client downloads emails and usually deletes them from the server.
• Not designed for synchronizing mail across multiple devices.

Example: you set up a mail client with POP protocol, and upon connection, it downloads all new emails to your computer, after which they are deleted from the server.