(jar) A COMpressed archive file containing Javaclass files, filename extension: ".jar". The Java Development Kit contains a tool called "jar" for creating .jar files, similar to the standard UnixtarCOMmand. As well as archiving and COMpressing the Java class files, it also inserts a "manifest" file which can contain information about the class files, such as a {digital signature}. COMbining class files into a single archive file makes it possible to download them in a single HTTP transaction. This, and the COMpression, speeds up execution of Java programs delivered via the Internet. (2001}-02-03)