Darknet

A darknet is a private online file distribution structure. A darknet enables for anonymous sharing since all users are connected without the IP address being publically shared.
Darknets do not use servers in which to host the information, instead it is distributed among the users and then seeded to the user who requests the file (All users with the file send data packets to the recipient which are then assembled).
Darknets tend to be used for users who wish to perform illegal activity with a higher level of anonymity (however darknets themselves are not illegal).