SASS/SCSS is the compiled version of CSS, it allows CSS to be written in a more dynamic and reusable way. The philosophy is make CSS, a very static language, into something that is more similar to a scripting language, then the SCSS file is then compiled back into a normal CSS file to be deployed. y introducing variables and splitting the single CSS file into different SASS/SCSS files (will be combined into one when releasing), this makes the CSS much easier to read and more maintainable. This is especially true when more than one developer is working on the same code base.

I personally prefer SCSS over SASS, to be honest there’s not much difference between the two. I like SCSS because of it uses brackets to show the scope instead of just indentation. Curly brackets makes nested code much easier to read, this is very important since that is how to write CSS or SASS/SCSS.

Here is the official site, which will explain everything in more depth with examples.