A JavaServer page (JSP) is a template for a Web page that uses Java code to generate an HTML document dynamically. JSPs are run in a server-side component known as a JSP container, which translates them into equivalent Java servlets.

For this reason, servlets and JSP pages are intimately related. What’s possible in one is, in large part, also possible in another, although each technology has its individual strengths. Because they are servlets, JSP pages have all the advantages of servlets:

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  They have better performance and scalability than CGI scripts because they are persistent in memory and multithreaded.
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  No special client setup is required.
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  They have built-in support for HTTP sessions, which makes application programming possible.
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  They have full access to Java technology–network awareness, threads, and database connectivity—without the limitations of client-side applets.

But, in addition, JSP pages have advantages of their own:

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  They are automatically recompiled when necessary.
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  Because they exist in the ordinary Web server document space, addressing JSP pages is simpler than addressing servlets.
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  Because JSP pages are HTML-like, they have greater compatibility with Web development tools.