If you install a current version of the uTorrent bittorrent client, be very careful with what you select during installation as it’s designed to catch you out and ensure that you install the uTorrent Toolbar and something called Conduit Search, which will thereafter appear all over all your web browsers. Should you want to uninstall all the extra junk (which does who knows what), you’ll find that there is no Uninstall button and you have to do it the hard way.
The same or similar remarks may apply to other bittorrent clients.