JAR, Java Archive File (.jar)
The JAR Archive file format
JAR is a framework used to group different classes of java files (programs and software) and other resources and data related to it (images, texts, etc). Thus, their further easy distribution across the java platform has been simplified and became more user friendly. With JRE installed on computers and mobile phones, it can run as an independent program as well as serve as a program library. They are used by mobile games to store game data, and Mozilla Firefox, Thunderbird, and other products to store themes and add-ons.
Technical details of JAR files
Built on the ZIP file format, the JAR files can be retrieved or developed from scratch using the jar command and tools provided by JDK. An option to digitally sign those archives using the jarsign tools is also available. These files serve an extensive purpose for they also support optional manifest files, CLASS files, and application resources.