If you just want to use a .JAR file then double-click it (can work the same way as a .EXE file). If that doesnt work, install Java 1.5 and try again. Some JARs dont contain programs, only parts of programs for other programs to use, so they cant open when you double-click them. Unlike EXE and ZIP, JAR can be put inside a rectangle in a webpage (applet) and it moves and reacts to mouse and keyboard. A Java program within a webpage. A .JAR file is similar to .EXE and .ZIP It is created by Java. Java uses .java files to build .jar and .class files, which other programs often use, or they could be a finished program that a Human uses. Like a ZIP, JAR contains folders and subfolders of files. Most files are Java code files (usually .class) JAR often contains a file called Manifest.mf that tells your computer how to start the program in the JAR. If there is no Manifest.mf then the program cant open automatically when you double-click the JAR. JAR files can contain and/or use other JAR files, other programs. They can contain any type and size of file. Use Winzip (www.winzip.com) to look at the files inside a JAR file. ------------------------------------------------------------------------------------------------- CodeSimian is a programming-language I built, which you can get as a single JAR file from these WEBSITES: www.codesimian.com codesimian.sourceforge.net ------------------------------------------------------------------------------------------------