This covers Ruby only, which is the main SASS compiler for many systems but other options exist. A very common one for any node developer would be node-sass which could be easier, and orders of magnitude faster, for many users.
Ruby comes pre-installed on a Mac computer.
Follow the instructions below to install Sass:
gem install sass
sudo gem install sass
sass -v
Ruby will need to be installed first before setup. You can install Ruby through the apt package manager, rbenv, or rvm.
Then Run
sudo su -c "gem install sass"
The fastest way to get Ruby on your Windows computer is to use Ruby Installer. It's a single-click installer that will get everything set up for you super fast. After installing Ruby, follow the instructions below to install Sass:
gem install sass
sudo gem install sass
sass -v