The terms stylesheets and cascading style sheets (CSS) simply refer to a way to declare how you want to display something in an HTML document. Stylesheets let you create a set of properties and apply that set of properties as needed, throughout your document or across many different documents in a site.
Why are stylesheets increasingly popular? Stylesheets allow you to:
Enforce a consistent look and feel across an application
Avoid retyping formatting tags and attributes
Change the appearance of a site with less effort
Choose from more formatting options
Link content (tags) with display (formatting)
The power of styles is that they are reused. One style ...