Even whole files can sometimes be completely unnecessary. The opposite of dead code is live, operational code. A special case is code that looks live but is still inoperational. This happens when dead procedures call other procedures. Even if there is a call, it is never executed.
Dead code is a very usual phenomenon.
This means excessive memory use and slower execution . Dead code also means more source code to read and maintain. This leads to higher costs , especially during maintenance. If the code is in there, programmers must spend time understanding it. Leaving dead code in a completed project means leaving untested code in it.