What is a 'Shell'?

Shell - A software interface between the user and the computer's operating system. The shell interprets commands entered by the user, and passes them on to the operating system. DOS shells are COMMAND.COM and DOS shell; some UNIX shells are the Bourne shell (sh), the C shell (csh), and the Korn shell (ksh).

This Q&A was found on XOOPS Web Application System : https://xoops.org/modules/smartfaq/faq.php?faqid=218