Answer: IRC

Internet Relay Chat is a method of communicating in real time, via text, over TCP/IP networks. Invented in 1988, it wasn’t widely adopted outside of academic and computer hobbyist circles in its infancy and thus, when the Soviet Union went into a state of media blackout in the summer of 1991 during the Soviet coup d’état attempt (the event which would ultimately lead to the dissolution of the Soviet Union), nobody thought to shut down IRC.

Throughout the conflict and media blackout, information flowed in and out of the Soviet Union via IRC when traditional channels like radio, telephone, and wire communications were held censored or shut down altogether.

Shortly before that, during the first Gulf War, IRC again saved the day by functioning as an efficient and unnoticed communication network left untouched by authorities.