Surge lets you remotely control the Transmission BitTorrent client. This means you can manage and add new torrents wherever you are, as long as you have an internet connection.
This gives you the advantage of knowing that you are not wasting expensive bandwidth, storage space or battery life on your device, as the actual downloading is performed remotely.
Please note: Surge is NOT a BitTorrent client and does not download any data itself. It can only be used to remotely control Transmission BitTorrent clients.