Part community and mostly file sharing, DC occupies an unusual niche in the P2P game. Unlike torrents, which are direct peer connections, or centralized networks like LimeWire, DC manages connections to hubs. Most hubs are built around an interest, such as science fiction or movies. From there, you can chat and share files with other peers who are connected to the same hub.
However, many hubs place restrictions on connections to ensure that users are devoting their attention to the hub. The number of hubs you can connect to depends on how many Upload share slots you give, and you rarely can connect to more than four or five hubs without violating the rules of at least one of them. That results in your connection to that hub being lost. Also, many hubs have a minimum share requirement, often 1GB or 5GB.
Connecting is rather simple. Once you install the program, you create a nickname, set your share directory, and the number of upload slots you'd like to give. There's a built-in public hub directory list to help users find communities they're interested in, which is searchable by keyword. Commands, such as to register your nickname with the hub so nobody else can use it, are entered into the main chat window.
There are a lot of mouse-over labels to help you understand what's going on, and since many of the communities are relatively small, people tend to be friendly in offering guidance. Hubs often employ a Help command to assist users in the rules and how-tos. Great for sharing files and chatting, DC has carved out a small but well-connected niche, and you can find most files you're looking for--as long as you're in the right hub.