Caller ID
North America · also called CID, calling line identification
The calling-party number (and optionally name) delivered with an incoming call — which can be spoofed.
Caller ID is the service that delivers the calling party's telephone number to the recipient, optionally accompanied by a name (CNAM). The number is signaled with the call; the name is typically looked up separately.
Caller ID can be falsified ("spoofed") because the calling number is asserted by the originating side. Combating illegal spoofing is the purpose of STIR/SHAKEN call authentication.
Caller ID is not proof of who is calling. The displayed number is asserted by the caller's side and can be spoofed; that is exactly what call-authentication frameworks were created to address.