Z shell

Z shell (zsh) is a Unix command-line interpreter shell created by Paul Falstad.

Description
Z shell is similar to, but not completely compatible with, (zsh), with many additions to accommodate  (csh) users while including some  (tsch) features. Zsh supports editing of multi-line commands in a single buffer; variable editing; a command buffer stack; recursive bing; manipulation of arrays; and spelling correction. zsh uses GNU and should compile and run on any modern version and some older versions of Unix.

Zsh on macOS
Bash had previously been the default command-line shell for Mac OS X since its NeXTSTEP origins. In 2019, Apple replaced bash with zsh in new installations of macOS Catalina (10.15). Upgrades to Catalina will retain the user's existing installation of bash with a notification in case the user would like to switch to zsh.