Zsh, also known as the Z shell, is a Unix shell that is built on top of bash (the default shell for macOS) with additional features. It is the default shell for macOS and Linux, and it is built as an extended version of Bourne Shell with a slew of improvements and features. Some of the key features of Zsh include:

• Plug-in support: Zsh includes many different plugin frameworks, which allow users to add new features and functionality to their shell.

• Better customization: Zsh offers more flexibility and a better user experience than Bash, with support for themes and other customization options.

• Spelling correction: If you make a minor mistake typing a directory name, Zsh will fix it for you.

• Automatic cd: Just type the name of the directory and Zsh will automatically change to that directory.

To use Zsh on a Mac, you can install a framework like Oh My Zsh or Prezto. The configuration file for Zsh is called .zshrc and lives in your home folder ( ~/.zshrc). To install Oh My Zsh, you can run the following command in your terminal: sh -c "$(curl -fsSL https://raw.githubusercontent.com/robbyrussell/oh-my-zsh/master/tools/install.sh)". The installation script should set Zsh to your default shell, but if it doesnt, you can do it manually by running chsh -s $(which zsh). To change the default shell in Terminal on a Mac, you can go to Terminal > Preferences > General, and then select the shell you want to use from the "Shells open with" dropdown menu.