What is the term for following someone through a secure door without authorization?

The term for following someone through a secure door without authorization is known as tailgating. Tailgating occurs when an unauthorized individual gains access to a restricted area by closely following an authorized person who uses a keycard, access token, or other means of entry. This tactic exploits the trust that individuals often have in one another, as they may not question the presence of someone immediately behind them who appears to be following them to the same destination.

While piggybacking is often used interchangeably with tailgating, it typically refers to a scenario where an authorized individual knowingly allows someone else to enter a secure area with them, which is slightly different in context. The focus in this particular situation is on the unauthorized access obtained by following someone without their consent. The other terms do not specifically capture the act of illicitly entering a secured area through the synchronized movement with an authorized person in such a way.