JAR stands for Java Archives. It consists of files that aggregate various Java class files, software, libraries, and metadata compressed and stored as a single unit. It is a cross-platform archive format. JAR contains manifest files, XML-based configurations, JSON data, texts, audio, images, etc. It works well with applets too. They are used for lossless data decompression, archiving, packing and unpacking of files, etc. Any Java Runtime Environment (JRE) can be linked to the java libraries within the JAR files. This makes code execution platform-independent.