Amazon introduced its widely anticipated television and movie download service Thursday, posing a new threat to Apple’s iTunes, which pioneered the market for online delivery of TV shows last year.

Amazon said the Amazon Unbox service includes thousands of TV shows, movies and other video from more than 30 partners. Users can download TV shows such as CBS’s “CSI” and “Numb3rs” and Fox’s “24” and “Prison Break,” as well as classics including all 79 episodes of the original “Star Trek.” Amazon has struck deals with A&E, Cartoon Network, Discovery Channel, FX, Comedy Central, Nickelodeon, MTV, VH1, HGTV and Fine Living. TV series are priced at $1.99 per show.

The online giant said the service offers a DVD-quality picture and includes a technology that allows consumers to buy video from one PC and download on another. The videos will be available on a personalized Web page on the Amazon site.

Amazon will face fierce competition in the suddenly hot download-to-own market. The launch has been widely expected in the television market for the past few months. It comes on the heels of AOL’s debut last month of a similar service. What’s more, TV networks are getting into the download-to-own business as well. Fox recently announced plans to offer TV shows across its network of Fox Interactive Media sites.