An unauthorized copy of a Japanese manga to be found on the internet. Name comes as the images from the manga are scanned on to the computer and its words translated into English, giving the final, most readable copy for viewership (in comparison to a raw, which is the original scan of the manga). Is useful for several things, mostly giving readers access to manga that they can't find or they want to see the next chapter of, or just giving free and complete access to a manga.
Person1: Gahhhhh, that new chapter of Bleach won't be in America for months, but it is already in Japan.
Person2: Just find a scanlation online, those appear regularly.
Person1: Really??? MUST. READ. NOW.