LESS is a CSS preprocessor language that extends your stylesheets with dynamic features. It was developed by Alexis Sellier with the main goal to make coding of stylesheets more efficient and to avoid code redundancy. The open source language can be seen as a superset of CSS as it uses the existing CSS syntax. Therefore valid CSS is also valid LESS code. The most crucial benefits LESS provides you with are variables, nesting, mixins, operators and functions.