What is the difference between EAR, JAR and WAR file

In J2EE application modules are packaged as EAR, JAR and WAR based on their functionality:

JAR: EJB modules which contains enterprise java beans class files and EJB deployment descriptor are packed as JAR files with .jar extenstion

WAR: Web modules which contains Servlet class files,JSP FIles,supporting files, GIF and HTML files are packaged as JAR file with .war( web achive) extension

EAR: All above files(.jar and .war) are packaged as JAR file with .ear ( enterprise archive) extension and deployed into Application Server.

Source: GeekInterview