An important component of the design of an information system is the design of the physical architecture layer, which describes the system"s hardware, software, and network environment. A three tiered architecture uses three sets of computers. The software on the client computer is responsible for presentation logic. An application server(s) responsible for the application logic. A separate database server(s) is responsible for data access logic and data storage. N-tiered architecture uses more than three sets of computers. A database server(s) is responsible for the data access logic and data storage. The application logic is spread across two or more different sets of servers. The second component us a web server that responds to the user"s requests, either by providing (html) pages and graphics (application logic) or by sending the request to. The third component (a set of twenty-eight programs written in the c programming language) on another application server that performs various functions (application logic).