What is File sharing?
File hsaring is common based on the peer-to peer model, a file is stored on a personal computer and can be distributed by connecting the two computers. Most people who engage in file sharing on the Internet both provide (upload) files and receive files (download).
P2P file sharing is distinct from file trading in that downloading files from a P2P network does not require uploading, although some networks either provide incentives for uploading such as credits or forcing the sharing of files being currently downloaded.
More information: Wikipedia
