CSS stands for Cascading Style Sheets.CSS saves a lot of work.Before learning CSS we should know the basics of HTML.CSS stands for Cascading Style Sheets.Styles define how to display HTML elements.Styles were added to HTML 4.0 to solve a problem.External Style Sheets can save a lot of work.External Style Sheets are stored in CSS files.CSS defines HOW HTML elements are to be displayed.Styles are normally saved in external .css files. External style sheets enable you to change the appearance and layout of all the pages in a Web site, just by editing one single file.CSS Syntax, a CSS rule has two main parts: a selector, and one or more declarations.The selector is normally the HTML element you want to style.Each declaration consists of a property and a value.The property is the style attribute you want to change. Each property has a value.A CSS declaration always ends with a semicolon, and declaration groups are surrounded by curly brackets.Comments are used to explain your code, and may help you when you edit the source code at a later date. Comments are ignored by browsers.A CSS comment begins with “/*”, and ends with “*/”, like this.In addition to setting a style for a HTML element, CSS allows you to specify your own selectors called “id” and “class”.The id selector is used to specify a style for a single, unique element.The id selector uses the id attribute of the HTML element, and is defined with a “#”.The style rule below will be applied to the element with id=”para1″.The class selector is used to specify a style for a group of elements. Unlike the id selector, the class selector is most often used on several elements.This allows you to set a particular style for many HTML elements with the same class.The class selector uses the HTML class attribute, and is defined with a “.”.There are three ways of inserting a style sheet:External style sheet,Internal style sheet, In-line style sheets.