Java is a full featured object oriented language. It is suitable for developing large scale applications. Applets can be used to develop many applications but there are strict rules enforced by the Web browser that limit how an applet can use the client system's network connection and hard drive (there are no such restrictions on Java applications). Still, this makes it possible to embed a spreadsheet or wordprocessor into a Web page as an applet. Applets can also be used to extend the functionality of a Web browser. For example, an applet could handle image or audio formats that the browser would otherwise pass on to a helper application, allowing the data to be displayed within the browser window.
An applet is embedded with the <APPLET> tag. It has many attributes including CODE for specifying the URL of the Java applet (appletname.class) as well as attributes for customizing the amount of space available to the applet within the browser window.