JavaScript

JavaScript is a scripting language developed by Sun Microsystems, Inc.  that uses the Java  language to perform various functions on Web pages. A scripting language is a specialized programming language that usually has fewer and simpler commands than a general programming language such as Java or C++.

JavaScript can be used on a Web page to check that all the information a user has entered into a form is formatted correctly and that all required information is present. It can also be used to display time in a particular format on a Web page, automatically format the data a user enters, or change an image when you move your mouse over it.