Homebrew or simply brew is a package manager which helps install and manage lots of Unix tools and software on your OS X.
It doesn’t come with OS X El Capitan, but it can be installed manually.
If you don’t have Xcode installed on your computer than you have to download and install up-to-date Xcode version from this page https://developer.apple.com/xcode/download/. On the moment I’m writing this the last version is 7.3.1.
Then install Xcode command line developer tools with the following command at your terminal
This will open dialog window guiding you through the installation.
And we are finally ready to download and install Homebrew, to do it just execute
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
And then test it with