Multiple Styles Will Cascade Into One

Style sheets allow style information to be specified in many ways. Styles can be specified inside a single HTML element, inside the  element of an HTML page, or in an external CSS file. Even multiple external style sheets can be referenced inside a single HTML document.  
  
 Cascading Order
  
 What style will be used when there is more than one style specified for an HTML element?
   
Generally speaking we can say that all the styles will "cascade" into a new "virtual" style sheet by the following rules, where number four has the highest priority: 
 
Browser default
External style sheet
Internal style sheet (inside the  tag)
Inline style (inside an HTML element)
 
So, an inline style (inside an HTML element) has the highest priority, which means that it will override a style declared inside the  tag, in an external style sheet, or in a browser (a default value).

Style Sheets Can Save a Lot of Work

Styles sheets define HOW HTML elements are to be displayed, just like the font tag and the color attribute in HTML 3.2. Styles are normally saved in external .css files. External style sheets enable you to change the appearance and layout of all the pages in your Web, just by editing one single CSS document!

CSS is a breakthrough in Web design because it allows developers to control the style and layout of multiple Web pages all at once. As a Web developer you can define a style for each HTML element and apply it to as many Web pages as you want. To make a global change, simply change the style, and all elements in the Web are updated automatically.

What is CSS?

• CSS stands for Cascading Style Sheets
• Styles define how to display HTML elements
• Styles are normally stored in Style Sheets
• Styles were added to HTML 4.0 to solve a problem
• External Style Sheets can save you a lot of work
• External Style Sheets are stored in CSS files
• Multiple style definitions will cascade into one