Java Archive (a compressed file containing a package of Java application-related files)
A JAR file may be compressed using zip compression and contains such things as the class, image, sound files and an optional manifest file.
A JAR file can also be used to deliver an off the shelf open source package run with XML data or, on the web, the file can be downloaded along with the page and then opened as the webpage is received and displayed.
MIME type: application/java-archive, application/x-java-archive
Learn more about JAR files:
Visit the Java website.
Search for answers to JAR-related questions at IT Knowledge Exchange.