Homebrew is a third-party package manager for MacOS which makes it easy to install and keep packages up to date. Instructions on how to install Homebrew are available on https://brew.sh, and, as of the moment of writing this book, consist of a single line executed in the following Command line:
$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
The following screenshot shows the list of operations you will then see Homebrew perform during installation:
Hit Enter to continue.