Why Servlets?

Portable. Servlet code is part of Java. Run on any platform that runs Java.
Power of Java APIs is available: networking, URL, multithreading, image manipulation, data compression, database connectivity, serialization, RMI, etc.
Efficient invocation. Once a servlet is loaded it remains in memory as one instance.
Safety. Type safety of Java language. Exception mechanism of Java.
Object oriented language with clean Servlet API.
Tight integration with server.
Flexible. Servlets can create content by println, Java objects, or XML-to-XHTML transformation.