Homebrew
Homebrew is a free and open-source package manager used for macOS systems and is an essential tool for developers or penetration testers using macOS. It allows easy installation of many standard tools without the hustle of manually compiling open-source tools or downloading their requirements. For example, php used to come built-in with macOS but has been removed from recent versions for 'security concerns'. Installing php without Homebrew requires the manual compilation of the php tool, which can take some time and be quite problematic. This is why PHP officially recommends using Homebrew to install it on recent versions of macOS. The same applies to many other developer tools.
Installation
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
To update brew:
brew update-reset
To check which packages are installed
brew list
Source: https://mkyong.com/mac/how-to-find-all-packages-installed-using-homebrew/
List of Homebrew packages
Get info about package
brew info transmission
Search for package
brew search firefox