The document explains three methods for applying CSS: inline, internal, and external. Inline CSS uses the 'style' attribute within HTML elements, while internal CSS employs the '<style>' tag in the document's head. External CSS involves linking to an external stylesheet for styling.

1. HowisCSSapplied?
Inline, Internal and External CSS

2. InlineCSS
UsingtheHTMLattributestyleonanelement

3. InternalCSS
UsingtheHTMLtag<style>inthehead

4. ExternalCSS
Linkingtoanexternalstylesheet