Direct connect aka neomodus is a filesharing program where you connect to a "hub" that has a main server, and hundreds or thousands of users connected to that server. hubs usually are organized by a common intrest, like all anime, all pron, all vcds, all dvd rips, all mp3 albums, all wares, etc etc. it is possible to be connected to multiple hubs. Hubs usually have rules set for minimum bandwith, minimum gb of shared files, min # of upload slots, content of shared files, etc etc etc.

dc++ is the preferred interface for dc use. search for it on the web. also search for neo-modus for a more in depth explanation of what it is/ how it works