What are the differences between Ear, Jar and War files? Under what circumstances should we use each one?

 #   There are no structural differences between the files;
they are all archived using zip-jar compression.
However, they are intended for different purposes.

#   Jar files (files with a .jar extension) arre
intended to hold generic libraries of Java classes,
resources, auxiliary files, etc.

#  War files (files with a .war extension) arre
intended to contain complete Web applications. In this
context, a Web application is defined as a single
group of files, classes, resources, .jar files that
can be packaged and accessed as one servlet context.

#   Ear files (files with a .ear extension) arre
intended to contain complete enterprise applications.
In this context, an enterprise application is defined
as a collection of .jar files, resources, classes, and
multiple Web applications.

#  Each type of file (.jar, .war, .ear) is processed
uniquely by application servers, servlet containers,
EJB containers, etc.