What is CSS? CSS stands for Cascading Style Sheets and it is the language used to style the visual presentation of web pages. CSS is the language that tells web browsers how to render the different parts of a web page. Every item or element on a web page is part of a document written in a markup language. CSS What is CSS. Cascading Style Sheets (CSS) are .css files that contain a collection of formatting rules that control the appearance of content in a web page. They are very useful for maintaining a web site since its appearance (controlled by properties of HTML tags) can be managed from just one file. Basic CSS Tutorial. STUDY. Flashcards. ... The basics of Cascading Style Sheets. ... Cascading order What style will be used when there is more than one style ... Integrate CSS commands into the head of each of your documents. Use the style attribute to put CSS code directly into a HTML element. CSS allows you to use all three of these methods in glorious tandem, inheriting and overriding values as you go (we’ll get on to all that in the next tutorial). CS142 Lecture Notes - CSS Key concept: Separate style from content Content (what to display) is in HTML files Formatting information (how to display it) is in separate style sheets (.css files).