If you are a frontend developer, you already know how important it is to write proper CSS for your website. Actually, CSS code doesn't have a direct relationship with performance optimization apart from style sheets' file size and duplicated classes. However, if you are planning to write code that is future-ready and easily maintainable, using a CSS preprocessor will ease your workload.
Of course, if you are working on a simple website, a preprocessor might not be required always. But, if you are working on a larger website and you have to deal with multiple style sheets and many CSS rules, a preprocessor will come in handy and will improve your code's quality.
In this section, I will briefly discuss SASS and LESS, the most popular CSS preprocessors available out there.