Compass functions as a framework for CSS. Sometimes CSS (Cascading Style Sheets) can become overly complicated; Compass addresses this problem by offering ways to simplify the coding process.
Cascading Style Sheets; while HTML dictates the content of page, CSS regulates the format, including headers, footers, navigation bars, etc. While all of these elements can be created in HTML, such a method would have to be repeated on every web page. CSS on the other hand, is applied to all pages of a website.