Cascading Style Sheets have been around for a while now, and act as a complement to plain old HTML files. If you're new to HTML, then take a couple of minutes to learn a thing of two... you'll be surprised what you can do with style sheets!
Cascading Style Sheets: The How and the Why - Cascading whats? (Page 2 of 6 )
Cascading Style Sheets…that's what! They're what paint is to canvas, what topping is to ice cream… they complement HTML and allow us to define the style (look and feel) for our entire site in just one file!
Cascading style sheets were introduced to the web development world way back in 1996. They get their name from the fact that each different style declaration can be “cascaded” under the one above it, forming a parent-child relationship between the styles.
They were quickly standardized, and both Internet Explorer and Netscape built their latest browser releases to match the CSS standard (or, to match it as closely as they could).
So, you're still asking what a style sheet exactly is? A style sheet is a free-flowing document that can either be referenced by, or included into a HTML document. Style sheets use blocks of formatted code to define styles for existing HTML elements, or new styles, called classes.
Style sheets can be used to change the height of some text, to change the background color of a page, to set the default border color of a table…the list goes on and on. Put simply though, style sheets are used to set the formatting, color scheme and style of an HTML page.
Style sheets should be used instead of the standard <font>, <b>, <i> and <u> tags because:
One style sheet can be referenced from many pages, meaning that each file is kept to a minimum size and only requires only extra line to load the external style sheet file
If you ever need to change any part of your sites look/feel, it can be done quickly and only needs to be done in one place: the style sheet.
With cascading style sheets, there are many, many page attributes that simply cannot be set without them: individual tags can have different background colors, borders, indents, shadows, etc.