distributed data network
A data network is composed of nodes which transmit messages. Most actual data networks are electronic, but one can imagine a bunch of children scattered about a playground holding tin-can telephones. Each child, acting as a node, has a few of these telephones. A message sent from a child at one end of the playground to one at the other end would typically be received and retransmitted by several other children, and could follow one of many different routes. An obvious problem with such a network is that it could quickly get clogged by messages; while a child tried to shout one message, new ones would be coming in.
A store-and-forward communication network allows nodes to handle simultaneous incoming and outgoing messages. In our playground model, imagine each child having a tape recorder attached to each of their tin cans. If many messages came in at the same time, or new messages came in while they were sending old ones, the children would just wait until the messages finished, then play the recordings to send the messages on their way. There are clearly many issues involved in making such a system work, even if you're using computers and telephone lines instead of children and tin cans.