Mainly to reflect the switch from tape media to optical media. The first among these was Kodansha, who used OAD to denote original anime episodes bundled with their manga volumes, but the term quickly got adopted by others as well.
A variant term for OAV/OVA—one or more anime “episodes” not produced for TV, but made to be sold directly on DVD/BluRay. Historically speaking, OAVs (Original Animated Videos) used to be whole anime franchises in the 80s or 90 that once existed entirely separate from the world of TV anime series.
In anime, an OAD is an Original Animation DVD. Sometimes, these are referred to as OAVs or, Original Animation Videos. In anime, an OVA is an Original video animation.
On top of that, not all OADs are canon. Many of them are essentially filler for the anime and do nothing for the overall plotline, while others are an important part of the storyline with key information between seasons. A good example of this is Fullmetal Alchemist.
Originally Answered: What does "OAD" and "OVA" mean in the context of anime? Original Video Animation (OVA) are anime that don't get released on TV, equivalent to straight-to-video movies like The Lion King 2 or Mulan 2.
Specifically, the term OAD refers to companion DVD's that are bundled with a source manga. Source: Original video animation. 66.4K views.
Anime/Manga market in japan still relies on physical distribution of manga or DVDs .So, OVA: Are intended for the smaller number of viewer who buy the DVD . Generally,OVAs are not associated with a show,i.e they are mostly non cannonical .
An OVA, which stands for Original Video Anime, is basically an anime that’s released straight to the home video market without airing on TV or getting a movie theater run first. They’re also sometimes called OAVs. Sometimes they’re basically bonus episodes for a TV anime, yes, but that’s not always the case.
Anime movie: As it suggest , it is a movie , it is shown only in theaters . Now , when the anime has stopped airing or has finished a season,a DVD or BD is released with all the episodes and specials of that season for that particular show , It is often here that OVAs are added to the DVD.
Mirai Nikki is a good one that comes to mind. While you don' t miss out on the anything in original ending it seems a little ambiguous in my opinion. The OVA highlights the how the ending came to be and it was actually one of the better OVAs I have seen.
Sometimes they’re basically bonus episodes for a TV anime, yes, but that’s not always the case. Sometimes they’re like the Dragon Half or Angel Sanctuary OVAs where there is no TV anime and instead they’re partially a bonus for the fans of the manga and partially a way to promote the manga to draw more fans in.