BitTorrent claims over 160 million users around the world. Content providers may balk, but the BitTorrent protocol itself is legal, and there's plenty of legal content to be found with it—from independent label music to high-definition videos, open-source app distributions, audiobooks, and more. It also remains the fastest way to transfer large files over the Internet. BitTorrent 6.2 for Windows, the company's own mainline client, now features a bandwidth scheduler, plus global and per-torrent speed limiting; both features help manage available bandwidth. In fact, BitTorrent 6.2 includes the same code as the much-loved uTorrent client, at least for its PC and Mac versions—and is virtually indistinguishable except for its larger installer.

It's important to further separate the BitTorrent protocol from the BitTorrent 6.2 client. The protocol describes a method of peer-to-peer file sharing, which lets users download a large file quickly while simultaneously sharing parts of it in the other direction to help other users. The client, meanwhile, is the company's own front end for users. Other companies also make BitTorrent clients with different names, but that use the same protocol underneath. Torrents, meanwhile, are little files you get that contain the data necessary for downloading the actual content you want—sort of like URLs for visiting Web sites. (For more on the basics of file sharing, check out our previous roundup, which explains most of the main concepts.)

The last time we reviewed BitTorrent was for version 4.2. Since then, BitTorrent bought uTorrent in December 2006, and has incorporated the code into its own mainline client. That's a good thing. As the company puts it, BitTorrent 6 bundles uTorrent's user interface and lightweight, streamlined kernel with BitTorrent's own peer-to-peer networking backbone. That said, BitTorrent 6.2 is a 3.1MB download; not huge, but heftier than uTorrent's lightweight 280KB installer. According to a BitTorrent product manager, BitTorrent 6.2 is larger because it uses a different installer and bundles the Ask.com toolbar. uTorrent also offers to install the Ask.com toolbar, but will download it separately from the Internet if you want it. The separate DNA client intended for content publishers is no longer part of the BitTorrent install.

The main BitTorrent 6.2 window is a little intimidating if you haven't used a torrent client before. A row of colorful icons adorns the top; most are shaped like media controls. In the bottom-right frame, seven tabs track download history, current transfer status, trackers (servers) and peers (other clients), file history, visual diagnostics for measuring speed, and an event log. To start sharing files, leave everything as is and begin adding torrents: Either click File -> Add Torrent, double-click a .torrent file (if you agreed to let BitTorrent associate the file type the first time you started the program), or click File -> Add Torrent from URL and key in the URL directly.

In a series of tests, BitTorrent's mainline client worked pretty much as advertised. I had no problem adding torrents, seeding (making files available for download), or prioritizing bandwidth. Downloaded files appeared in my user folder, and everything I downloaded worked fine during the test. Once a few torrents are downloading, you can begin tweaking the app's performance. As you add torrents, they appear in the main window along with helpful transfer speed statistics. Right-click on a torrent to see options to adjust bandwidth allocation (high, normal, or low), or set download and upload speed limits (25 to 1,000 KBps for downloads, 5 to 25 KBps for uploads, with unlimited options for either).

Once a torrent is finished downloading, the client by default keeps seeding it to other users; if you want, you can remove the torrent, with options to delete the corresponding .torrent and other data files. Highlight a torrent with the cursor, and you can click through the tabs across the bottom to monitor availability, peers, transfer times, individual files that compromise the torrent, and other data. As with uTorrent, there is a scheduler and RSS downloader for those interested in managing bandwidth consumption or subscribing to new .torrents.

If you're looking for a stronger media experience, I'd say give Vuze 4.2 a look. It's decidedly more bloated, and tends to alienate hard-core file sharers. But it includes plenty of media discovery options for standard- and high-definition video—including ad-supported legal sources like the BBC and PBS. Otherwise, aside from the availability of the Linux version of BitTorrent 6.2, most folks can safely choose uTorrent instead. It's a smaller install and does almost exactly the same thing with the same interface. In the end, it's probably best for BitTorrent to just combine the two and end the confusion.

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