Algorithm, Search & Distribution
Indexing
Also called: indexed, search index
Before anything can rank it has to be indexed, which means the system has crawled it, worked out enough about it and filed it somewhere it can query in milliseconds. YouTube indexes a video's title, description, captions and the audio and visual content itself. Google indexes pages. A private or unlisted video sits outside the public index entirely, so nobody reaches it through search however well it is written. Being indexed is only the entry ticket, and it says nothing at all about whether you will actually be shown to anybody.