SASS (Syntactically awesome style sheets) is an extension of the CSS which adds syntactic power to the basic CSS language making it easier for developers to write CSS. In simple words, it is just a CSS pre-processor, so that you can write CSS in an easy and convenient way.
There are two syntaxes of SASS i.e SCSS and SASS with two different file extensions
The sassy CSS or just SCSS is the most commonly used. The syntax of SCSS is similar to the CSS3 syntax. Hence we can say that every CSS3 stylesheet is SCSS as well.
While the SASS is the older version, one of the major differences in writing these two is the use of semicolons and brackets.