<li>Torrent files contain information about the actual file you want to download (eg a movie), and connect you to the swarm of peers sharing it.</li>
<li>Transmission can watch a certain folder (eg your Safari download folder) for torrent files and then open them automatically via Preferences >> Transfers >> General.</li>
<li>By default, Transmission deletes the original torrent file upon opening. If you remove a transfer, in order to resume it you will need to reopen the original torrent file in Transmission.