Did you know...
CSS is a TLA
A TLA is a Three Letter Acronym.
CSS stands for Cascading Style Sheets

CSS is the technology that controls the look of a web page or application written using web technologies (HTML, CSS, and Javascript). These days, there is many other kinds of stylesheets (SASS, LESS, SCSS), but CSS is the core technology that controls look (the others are what are known as CSS pre-processors and they output CSS).