What is a preprocessor for CSS? Sass, Less, and Stylus are what? Why are they used?

The usage of complex logical syntax like variables, functions, mixins, and code layering is made possible by the CSS preprocessor, a program that improves the fundamental functioning of vanilla CSS scripts.

The.sass extension is used by Sass (Syntactically Awesome Style Sheets). It does not use curly brackets or semicolons; it is just used for indentation.

It does not use curly brackets or semicolons; it is just used for indentation.

The .less extension is used by Less (Leener Stylesheets). Using NPM or a less.js file makes adding it to any JavaScript project simple. The variables in this case are defined using @.

The writing syntax is very flexible when using a stylus. It may exclude brackets, colons, and semicolons in addition to using native CSS. It is not necessary to specify the variables with @ or $.

People use SASS, LESS, and Stylus in order to extend the basic functionality of vanilla CSS.