BitTorrent is popular peer-to-peer sharing communication protocol used for transferring all kind of files over the Internet. Two of the most popular BitTorrent clients for Linux are Azureus and KTorrent. If you're looking for a robust, fast, simple, and powerful BitTorrent client, you will probably go with KTorrent. If you want a Java-based client that runs on every platform and allows you to configure every detail for BitTorrent transfer, consider Azureus.
Both Azureus and KTorrent are feature-rich and powerful BitTorrent clients with powerful file transfer management GUIs, statistics, and highly configurable settings menus. Azureus is written in Java and therefore can be run on practically all platforms, while KTorrent is written in C/C++ using Trolltech's Qt toolkit, and can be run only on Linux and Unix-like systems (including Mac OS X).