It provides the advantages of /bin/csh for interactive use, while staying clear of its broken design and remaining compatible with /bin/sh. Consequently, it was the favourite shell for many power users on Unix systems throughout the 80s. Unfortunately, it was proprietary code, and it only came with commercial SysV-based Unix (which is codified in POSIX} standards).

When the 1993 Korn shell version was put in the [public domain, an independent attempt to recreate ksh, bash, has already gained serious popularity. Meanwhile, ksh development continues, as do the POSIX standards. As a consequence, if you want to find a Korn-compatible shell there are three names to look for: ksh, pdksh, and bash.