A Java Archive (JAR) file is a platform-independent file format that collects many files into one. For example, multiple applets written in the Java programming language, and their requisite components (.class files, images, sounds, and other resource files) can be bundled in a JAR file and subsequently downloaded to a browser in a single HTTP transaction. JAR files support file compression and digital signatures. Their standard file extension is .jar.
WebSphere Application Server uses the standard JAR file format to package modules, regardless of the type of module. However, the archive file is referred to according to its content: