A distributed data store is a network in which a user stores his or her information on a number of peer network nodes. The user also usually reciprocates and allows users to use his or her computer as a storage node as well. Information may or may not be accessible to other users depending on the design of the network.
Most of the peer to peer networks do not have distributed data stores in that the user's data is only available when their node is on the network. However, this distinction is somewhat blurred in a system such as BitTorrent, where it is possible for the originating node to go offline but the content to continue to be served. Still, this is only the case for individual files requested by the redistributors, as contrasted with a network such as Freenet where all computers are made available to serve all files.
Distributed data stores typically use an error detection and correction technique. Some distributed data stores (such as Parchive over NNTP) use forward error correction techniques to recover the original file when parts of that file are damaged or unavailable. Others try again to download that file from a different mirror.