Korn Shell, also known as ksh, is a Unix shell developed by David Korn of AT&T Bell Laboratories. It is similar to the Bourne Shell, but with additional features and improvements in usability, as well as backwards compatibility with Bourne Shell scripts. Korn Shell is popular among Unix and Linux users and is used for writing scripts and automating tasks. Proficiency in Korn Shell is often required for Unix/Linux system administration and software development roles.