Original net animation (ONA) is used in Japan for anime titles that are directly released onto the Internet. It is a relatively new form of animation distribution that has not been widely adopted, but has been made possible by the increasing amount of Internet Streaming media websites in Japan. Basically, this means that an anime labeled as a type 'ONA' has been directly released on the internet, before being aired on television. The name mirrors original video animation, a term that has been used in the anime industry for straight-to-video animation since the early 1980s. A growing number of trailers and preview episodes of new anime have been released as ONA. For example, The Mastermind of Mirage Pokémon (which was only available through the Japanese official website from October 13, 2006 to October 30, 2006) and the anime movie of Megumi can be considered as ONAs in Japan.
ONAs tend to be fairly short, often spanning between 1 to 5 minutes.