A television pilot is the first episode of an intended TV series. While many pilots are shot, fewer make it to the screen, and even fewer go on to become full-fledged television series. Competition at the network level is intense, with advertising dollars and choice viewer demographics at stake. Before a network commits to funding an entire pilot episode, it often requests a pilot presentation, a one-day shoot that, when edited together, gives a general idea of the look and feel of the proposed show.
Pilots most often run in the fall television season, but also after the winter holiday hiatus, when mid-season replacement shows air to replace those shows cancelled mid-way through the year. More rarely, a pilot will air in summer, as was recently the case with The O.C.