A common problem for developers is to confuse the two programming languages Java and JavaScript. Although the two languages share some common features, are widely used in general and animals in various applications.
Java is a programming language commonly used in Sun Microsystems to come out as a form of "write once, run anywhere" programmers. Java code that runs on a virtual machine, and a Java application without the developer of the different architectures and operating systems that can run the application in question will be distributed.
You can, however, a scripting language. Its sole purpose is that Web pages. When a browser loads the page, insert the JavaScript code in it. The code can change the look of the site. For example, the JavaScript used to create a menu, create the extension, with the mouse, or an art gallery, where changes in the image appear from time to time.