What is Cascading Style Sheet?

Cascading Style Sheets (CSS) is a stylesheet language used to describe the presentation of a document written in HTML or XML (including XML dialects such as SVG, MathML or XHTML). CSS describes how elements should be rendered on screen, on paper, in speech, or on other media. CSS is commonly used to define the colors, fonts, layout, and other stylistic aspects of web pages and user interfaces.