Handle

A username, especially on social platforms. The part you @-mention. Often public, often global to that platform.

A handle is a synonym for username on social platforms. It's the part of your identity that other users will type when mentioning you, and it's typically global within that platform — meaning two users cannot share the same handle. Handles are distinct from display names, which are what gets shown in the UI and which can usually contain Unicode, emoji, and longer text.