CSS framework

A CSS framework is a library allowing for easier, more standards-compliant web design using the Cascading Style Sheets language. Most of these frameworks contain at least a grid. More functional frameworks also come with more features and additional JavaScript based functions, but are mostly design oriented and focused around interactive UI patterns. This detail differentiates CSS frameworks from other JavaScript frameworks.
Two notable and widely used examples are Bootstrap and Foundation.
CSS frameworks offer different modules and tools:
Bigger frameworks use a CSS interpreter like Less or Sass.