SCSS

SCSS is a special type of file for SASS, a program written in Ruby that assembles CSS style sheets for a browser.

SASS allows additional functionality to CSS, e.g. variables, nesting and more, which can make writing CSS easier and faster.

SCSS files are processed by the server, running a web APP to output traditional CSS that your browser can “understand”.

The advantage of using SCSS is that the syntax is almost the same, except for some extras which are easy to learn.

SCSS is fully compliant with CSS, which means you may simply rename CSS file to .scss and it will work.

It is good to know that almost all existing tools for SASS are developed using SCSS syntax, which becomes another advantage of using SCSS.

With the above being said, SCSS is a powerful tool, which makes stylesheets editing faster and more convenient.