A simulcast takes place when a program or event is simultaneously broadcast across more than one broadcast platform at the same time. For example, Virgin Radio is simulcast on both AM and on satellite radio; the BBC's Prom concerts are often simulcast on both BBC Radio 3 and BBC Television.

Simulcasts via satellite can be a challenge, as there is a significant delay because of the distance (nearly 50,000 miles or 80,000 km round-trip) involved. Anything involving video compression (and to some extent audio data compression) also has an additional significant delay, which is noticeable when watching local TV stations on direct broadcast satellites. Even though the process is not instantaneous, this is still considered a simulcast because it is not intentionally stored anywhere.

In horse racing, a simulcast is a broadcast of a horse race which allows wagering at two or more sites; the simulcast often involves the transmission of wagering information to a central site, so that all bettors may bet in the same betting pool, as well as the broadcast of the race.