- J -   jack in -- To log in to a machine or connect to a network. Derived from cyberpunk fiction.   Java -- An object oriented programming language created by Sun Microsystems. Java is a device independent language, meaning that programs compiled in Java can be run on any computer. Java programs can be run as a free-standing application or as an applet placed on a web page. Applets written in Java are served from a web site but executed on the client computer. Java applets have a built-in security feature which prevents them from accessing the file system of the client computer. See also applet. Here is the Java version of "Hello World!": class HelloWorld { public static void main (String args[]) { System.out.println("Hello World!"); } }   JavaScript -- A scripting language that allows lines of Java code to be inserted into HTML scripts.   Joint Photographic Experts Group -- (abbreviation: JPEG) An image compression standard for still photographs that is commonly used on the web.   JPEG -- See Joint Photographic Experts Group.