4. BitTorrent

Summary: BitTorrent has become so notorious for sucking up bandwidth that many ISPs, businesses, schools or anyone with a large network and fast Internet connection tries to limit its use. Some reports say it uses about one-third of the bandwidth on the planet! This powerhouse can move even the largest files, by breaking them up into pieces, running simultaneous downloads from multiple users and automatically reassembling the pieces.

There are some downsides, however. If very few people are seeding a torrent (i.e. have a complete copy of a file on their computer and are running a BitTorrent client) then it can take much longer to download. It is also possible to get stuck with an incomplete file if there are not enough seeds for a file. It is also often difficult to find legal torrents, or find torrents at all, since the BitTorrent client and website search feature is very basic.

Figure 2: BitTorrent User Interface (click to enlarge)

Speed: Download speed can be amazing, reaching 200 kB/s or more, if there are many "seeds" for the file. Since ISPs often block or limit this program, you can try changing the port used if you run into speed problems. But many ISPs use software that uses smarter techniques than just looking for certain ports, so changing the port number may not help.

You might also need to upgrade your router, since some popular routers can't handle the multiple connections that BitTorrent uses. This article has more info on that. Note that files available only from a single user will take a long time and are better to be downloaded through other engines.

Variety of Content: Whatever you can find a torrent (files in the special BitTorrent format with the ".torrent" file extension) for. BitTorrent has probably the largest variety of all, if you can find the right places to look!

Comments: There are many other clients such as azureus (Java based client) that provide tools to make sure certain ports are free. Both azureus and BitTorrent's client are available for both Windows and Linux. Almost all popular BitTorrent clients are lightweight, clean of adware, and easy to use. The files are also almost never corrupted.

BitComet

I'm singling out BitComet because it is the number one BitTorrent only client. This program has a very intuitive user interface coupled with a listing of all the latest torrent sites. This is a program that anyone can use with no special configuration. There are currently 20 million downloads of BitComet from Download.com. This puts this client in a strong fourth place among all file-sharing applications.

Figure 3: BitComet User Interface (click to enlarge)