The television season begins in September and ends at the beginning of summer, as of June 2015. However, season premiere dates vary depending on the show and the television network. Certain shows begin their seasons in January or in the summer.
By debuting new shows at the same time, the major television networks generate publicity for the upcoming television season. They can also sell advertising packages several months in advance.
Certain television networks, typically cable networks, don't follow the traditional television season and instead premiere new shows at any time during the year. Netflix also premieres shows throughout the year and in some cases releases the entire season of a show at once.