Apple announced today that all four of the major broadcast television networks are now offering HD content on iTunes.

In an age where it seems as though everyone has a DVR in one form or another, most cable systems offer “on-demand” service, and finding full-length episodes of your favorite TV programs on the Web is a piece of cake, Apple’s announcement that all four of the major broadcast television networks are now selling their offerings on iTunes comes as something of a surprise.

Apple claims that iTunes now has the world’s largest online catalog of TV programs, including all the prime-time shows from the ABC, CBS, Fox, and NBC television networks available in both standard and high definition. Apple has also convinced many of the cable networks—including HBO, Bravo, Comedy Central, ESPN, and MTV—to sell their wares on the online service.

The company reported today that it has delivered more than 200 million TV episodes to date, and that it has sold more than one million episodes in high definition since it began offering HD content on iTunes last month. There are currently 30,000 TV episodes and 2,500 films in the iTunes library.

Apple doesn’t disclose how much it pays the networks for their content, but with SD episodes selling for $1.99 each, and HD episodes going for $2.99 each (a “season pass” option allows customers to buy an entire season at a discounted price), iTunes must be generating a great deal of revenue.