What is Java Applets and Java Servlet ?

Java Applet

• An Java applet is a special kind of small Java program that is designed to be transmitted over the Internet and automatically executed by a Java-compatible web browser. 
• Applet are typically used to display data provided by the server, handle user input, or provide simple functions, such as a loan calculator, that execute locally on client machine, rather than on the server.
• An applet is downloaded on demand, without further interaction with the user. 
• When a user clicks a link that contains an applet, the applet will be automatically downloaded and run in the browser.
  

 Java Servlet:

• A servlet is a small program that executes on a server. 
• Servlets dynamically extend the functionality of a web server and applets dynamically extend the functionality of a web browser. 
• Java spanned both sides of the client/server connection with Applet and Servlet.

Java: The Complete Reference, Tenth Edition (Complete Reference Series)