A JAR file is a compressed/package file format that uses the same compression format and algorithms as a ZIP file. The JAR files usually contain various Java classes and meta-data.
The JAR files, also referred to as the Java ARchive, are usually regarded as the files that contain the images, classes and sound files of Java applications compressed together into one file. They have ".jar" file extension and are created by using the jar command. Zip tools can also be used to create a JAR files that allow Java runtimes to deploy a set of classes efficiently along with their associated resources.