Almost, but the indexer looks at all the torrent sites you tell it to.
So you could have it search torrentbay, 1337x, demonoid, and more (public, semi-private, and private). It will then pick the best torrent from all of them.
This is also helpful if one site it temporarily down, it still searches the others.
You can also set up some fancy rules if you want (for example download my movies from this one private tracker only, TV shows from these trackers, and music from any tracker) there’s also priority sorting, if your interested in that too.