Satellite was actually theorized by author and radar engineer Arthur C. Clark in 1945. The idea became a reality in the early 1960s, and it gave us the ability to nearly instantly see events happening anywhere on the globe rather than having to wait for film or tapes to reach broadcast stations.
The first communications satellite, Echo 1, was aptly named. It was a metallic balloon, 1,000 miles (1,609 kilometers) above the Earth, off of which signals could be reflected to other spots on the globe. The first active telecommunication satellite was Telstar 1, which launched in 1961 into low earth orbit, and allowed for TV, phone and fax delivery. With Telstar and the communications satellites that followed, worldwide instant televisual broadcasting became possible.
An early (and famous) demonstration of this was HBO's showing of a boxing heavyweight championship fight between Joe Frazier and Muhamad Ali called "The Thrilla from Manila," which was broadcast live to subscribers.
Satellite was first used to broadcast from locations to broadcast stations, which would then send the transmissions out to homes via traditional broadcast television channels. PBS even started broadcasting all its programming via satellite in 1978. But like cable, its name can mean the subscription service after which it is named now, too.
A breakthrough at Japan's NHK broadcasting service by engineer Yoshihiro Konishi allowed for a significant decrease in power output and increase in sensitivity of terrestrial satellite antennas, which led to satellite services such as Dish Network and DirectTV becoming competitors of broadcast and cable TV. Satellite can be broadcast over a much wider area than terrestrial towers, and became a method of getting reception, and more channels, in rural areas where cable lines had not been laid. At first, it was far more expensive than cable, but now it's comparably priced, so networks and individual consumers can get their programming from space.