A covert operation or undercover operation is a military or police operation involving a covert agent or troops acting under an assumed cover to conceal the identity of the party responsible. Some of the covert operations are also clandestine operations which are performed in secret and meant to stay secret, though many are not.

In law enforcement, a sting operation is a deceptive operation designed to catch a person attempting to commit a crime. A typical sting will have an undercover law enforcement officer, detective, or co-operative member of the public play a role as criminal partner or potential victim and go along with a suspect's actions to gather evidence of the suspect's wrongdoing. Mass media journalists occasionally resort to sting operations to record video and broadcast to expose criminal activity.