What is LESS& SASS subdivision of CSS

Question

I just went through well development tutorial there I got the information that we need to know any one of SASS or LESS . what are these ,how they differ ?Then what is these different from what we learnt?

Answer 1

What we learnt is plain CSS (which is quite powerful IMHO). For even more sophisticated functionalities, you may adopt a *CSS pre-processor* like Sass or LESS (or Stylus, according to what I've read):
https://www.keycdn.com/blog/sass-vs-less/

CSS pre-processors take one CSS with embedded scripting, and transform it into a plain CSS. The advantage is that, with the help of pre-processors, you can achieve quite complicated features (as loops, includes, etc.) with very few commands.