It is a torrent site that we use to download movies, software, games and much more. You download a link from 1337x, then you can use this link in any Torrent downloader to download the file using the BitTorrent protocol.
Although there is no Android or iOS app for 13377x, you can use this site on your phone. However, you can find the built-in BitTorrent or Utorrent app store that you can use to download the 13377x movie directly to your mobile device.
You can ask, hey writer, that there are a lot of torrent sites online, why do you insist on 1337x? I have reasons for this, dear reader. As far as I know, 1337x has the largest collection of movies, software, games and everything in between. Lots of new movies that I couldn't find on other websites located on this torrent website.