Zsh

ZSH is a shell, it is almost entirely backwards compatible with bash with several additional options.

Documentation

official docs	http://zsh.sourceforge.net/Doc/Release/index-frame.html
zsh manpages	https://manpages.debian.org/buster/zsh-common/index.html

Locations

~/.zshrc	rcfile
/usr/share/zsh/functions/Completion/*/*	builtin completions (see $fpath)
/usr/share/zsh/site-functions	third party zsh completions

Components

ZLE	[man zshzle https://man.archlinux.org/man/extra/zsh/zshzle.1.en]	zsh's line editor
compctl	[man zshcompctl https://man.archlinux.org/man/extra/zsh/zshcompctl.1.en]	original completion system
compsys	[man zshcompsys https://man.archlinux.org/man/extra/zsh/zshcompsys.1.en]	new completion system

Notes

zsh antigen

zsh plugins

zsh autocompletion