They use Google Analytics. Here's there post about it https://github.com/Homebrew/brew/blob/master/docs/Analytics.md https://github.com/Homebrew/brew/blob/maste

They use Google Analytics. Here's there post about it https://github.com/Homebrew/brew/blob/master/docs/Analytics.md https://github.com/Homebrew/brew/blob/master/docs/Analytics.... There are also instructions on how to opt-out.