Networked computers can send files and messages to each other. However this is a simplistic view of networking. Most networked computers tend to work in partnership to perform specific tasks. The diagram below shows a simplistic view of a web server. A web page request is sent from the users PC to the Web server. The web server then accesses a database, held on a separate PC, to access the required information to build the page. Finally the HTML is sent back to the user so they can view the final webpage. This is a simple example of a distributed system.

Most web servers have many computers providing the single service of a single website. Google, for example, will have many PC's serving search requests. The user has no idea that this is occurring and as far as they are concerned they are only talking to a single computer. The exact mechanics of how this works is far beyond the scope of this book.A lot of servers may have multiple processors installed and use the parallel architecture (this will be examined in A2)