This is another of those pages you don't have to memorize, but which we're providing here anyway in case you want the full story. They are just HTML or text files which are downloaded to your browser and displayed immediately. The server runs the program time.cgi and stores the output in its memory. The server then sends the output of the program to you.
Dynamic pages can get quite sophisticated.
Some return different results based on the arguments you supply when asking for a page. For example, our HTML page sizer prints out a set of directions if you load it without an argument. If you give it the name of a file, it prints something totally different. Give it a try.