log4j is a reliable, fast
and flexible logging framework (APIs) written in Java, which is distributed
under the Apache Software License.
log4j has been ported to the
C, C++, C#, Perl, Python, Ruby, and Eiffel languages.
log4j is highly configurable
through external configuration files at run time and it is basically used to
write our own logs inside the code so it would be easy to troubleshoot code in
case of any issue.