1. A method of providing content in a system where a content server and a plurality of user clients are in data communication with each other via a network, the method comprising: (a) receiving content information that each of the user clients stores, each of the plurality of user clients having a communication agent configured to communicate data with the content server or other user clients; (b) receiving a content request signal from a user client; and (c) providing information of nodes having the requested content based on the information received in (a) to the user client that has requested the content, wherein the communication agent controls the user client to establish connections with a plurality of nodes using the node information and to receive the requested content from at least one of the plurality of nodes by way of a parallel/distribution method.