Physically observing a user input a code or password is known as:

Social engineering is a broader category of manipulation techniques used to psychologically deceive individuals into revealing information or performing actions, not specifically limited to physical observation.

Shoulder surfing is a physical security attack where an attacker watches a victim enter credentials, PINs, or other sensitive input by looking over their shoulder or from a nearby vantage point, compromising information without any technical intrusion.

Tailgating is a physical security breach where an unauthorized person follows an authorized individual through a secured entry point, unrelated to observing credential input.

Phishing is a digital attack using fraudulent emails, messages, or websites to trick users into entering their credentials, which does not involve physical observation.