JSP enables the dynamic generation of web pages,similar to ASP.NET and PHP.
When someone visits a JSP page,the HTML web page is generated and sent back to the visitor. Below you can see the construction of a basic web page. The HTML source code on the side shows the output "The date today is".
In order for a static web page to show today's date,it would need to be edited every day and uploaded to the web server. This is very time consuming for such a simple task. This is where the dynamic generation of web pages is used.
In the JSP above,special syntax is used to signify that the current date needs to be displayed. You have probably seen this in the JSP tutorial already. This special syntax is processed on the web server and sent back to the visitor as a normal (html) web page.