Apple's #WWDC2019 (Worldwide Developers Conference) was held on June 3-7.
Details of the cool announcements  can be found here
https://developer.apple.com/wwdc19/

macOS's next big upgrade will be called Catalina and with it comes a big change for developers.
Catalina macOS

By default macOS has used bash as the default shell. New user accounts in macOS Catalina will use zsh. Zsh is an open source shell very popular and comes with a ton of features.

Zsh Shell

Zsh git repository link is https://github.com/robbyrussell/oh-my-zsh/

Apple support page contains details about how to set the Zsh shell as default for macOS Mojave and earlier https://support.apple.com/en-us/HT208050