CSS, which stands for Cascading Style Sheets, is a stylesheet language used for describing the presentation of a document written in HTML or XML. In simpler terms, CSS is used to style and format the visual presentation of web pages. Here's a basic introduction to CSS:

Selectors and Declarations:

CSS uses selectors to target HTML elements and declarations to define how those elements should be styled. A simple CSS rule looks like this:

selector {
  property: value;
}