POP3
POP3 (Post Office Protocol version 3) is an Internet standard protocol used by email clients to retrieve email messages from a mail server. It operates on port 110 (or port 995 with SSL/TLS encryption) and typically downloads messages to a local device, often deleting them from the server after retrieval. This protocol is designed for simple, offline email access, making it suitable for users who check email from a single device.
Developers should learn POP3 when building or maintaining email clients, integrating email functionality into applications, or troubleshooting email systems, as it's a foundational protocol for email retrieval. It's particularly useful in scenarios where users need offline access to emails, such as in desktop email applications or legacy systems, but it's less common in modern web-based email due to its lack of server-side synchronization features compared to IMAP.