seeding = hosting. tracker only keeps track of clients and seeds. clients pass around the bits of pieces of the file they do have to each other, and eventually become seeds. if there is no seed, they can only pass around an incomplete file. u need to seed till other people become seeds atleast or it collapses. if u do leave for a while, u gotta check back and make sure theres still seeds and help out, or it'll die. what makes torrent powerful is that it doesn't place all the burden on you. instead of having 100 people killing your connection each downloading their own copy straight from u, they all share the burden of passing around the packets they have ot each other starting from the few people directly connected to you. eh.. i think thats more or less it😛