A dynamic document is created by a Web server whenever a browser requests the
document. When a request arrives, the Web server runs an application program or a
script that creates the dynamic document. The server returns the output of the program
or script as a response to the browser that requested the document. Because a fresh
document is created for each request, the contents of a dynamic document may vary
from one request to another. A very simple example of a dynamic document is the
retrieval of the time and date from a server. Time and date are kinds of information
that are dynamic in that they change from moment to moment. The client can ask the
server to run a program such as the date program in UNIX and send the result of the
program to the client.