Netflix is currently the most successful movie service online, offering both streaming video and mail-order DVD rentals. As a subscriber, you browse an extensive catalog of movies and TV shows and create a list, or queue, of the things you want to see. Plans exist for one or more DVDs at a time. The DVDs arrive, usually within a few days, you watch them whenever you can and return them free of postage, and the next items on your queue are sent out.
Recently, an all-online option has become popular as the availability of streaming movies and TV has increased. Entire seasons of television shows are online, and agreements with some premium and broadcast channels make some available almost immediately after they air.
If you're interested in streaming free TV in a timely manner, another option is Hulu. Programs from NBC, Fox, ABC and many other networks and studios are available for free, although the service is ad-supported. While many popular shows are available the next day, there are specific agreements dictating which, and how many, episodes of each show are available at any time. Many of these restrictions are removed for members of Hulu Plus, a paid subscription service.