The search results come back the same way they progressed through the network. In this manner one is able to search several thousand computers. Chances are very high that one finds what one is looking for provided the network one is connected to be large and relevant. It is necessary to explain here the difference between a central index network and a true P2P network. Napster belongs to the first kind.
Central indexes are servers where indexes exist for clearly defined purposes like sharing music.
Central index networks are like websites in that sense, which can be searched and are highly dependent on the number of users connected to particular servers, the greater the number of users, slower the response and have a single point of failure. If the server fails, the service stops. It ensures that even if a couple of computers you are connected to go down, you always have two to three more to connect through. Currently P2P is much hyped and counts among its major applications something that is not totally legitimate i.e. sharing music online. However, in the near future it will have a huge impact on how people and organisations use the Internet and intranets to share, search and retrieve information and files easily across one's organisation or network.