SASS means Syntactically Awesome Stylesheets as a
CSS pre-processor
is a stylesheet language initially designed by Hampton Catlin and developed by Natalie Weizenbaum.After its initial versions, Weizenbaum and Chris Eppstein have continued to extend Sass with SassScript, a simple scripting language used in Sass files.
Sass is a scripting language that is interpreted into Cascading Style Sheets (CSS). SassScript is the scripting language itself. Sass consists of two syntaxes. The original syntax, called the indented syntax, uses a syntax similar to Haml. It uses indentation to separate code blocks and newline characters to separate rules. The newer syntax, SCSS, uses block formatting like that of CSS. It uses braces to denote code blocks and semicolons to separate lines within a block. The indented syntax and SCSS files are traditionally given the extensions .sass and .scss respectively.