values, you could later add the class as a style reference to a paragraph of text as follows: <head> <style> .myclass {font:Arial;} </style> </head> <body> <p class="myclass">Dorknozzle</p> </body> In this case, the rule is defined (as a document-wide style sheet) such that a class is set with the font property. The property value is set to Arial. The <p> tag uses the class, accessing it with the class attribute, and renders the text Dorknozzle as Arial in the browser. Pseudo-Classes: Pseudo-classes are similar to classes in that they define rules for use on your web pages. The difference between classes and pseudo-classes, however, is that pseudo-classes aren't applied to elements in your web pages as classes are. For the most part, pseudo-classes are reserved for modifying links, visited links, active links, and hover states for links. Here is an example of pseudo-classes in use: <head> <style> a.link {font:Arial; color:blue;} a.hover {color:Red;} </style> </head> <body> <a href="index.htm">Home</a> </body> In this case, the link and hover pseudo-classes are used to define the font and color of all hyperlinks on the page. Pseudo-classes are outlined with greater detail later in the chapter. ID: Generally used for JavaScript purposes, an ID allows you to set up a custom style as well as reference the uniquely named element from JavaScript. For instance, if you were to set up an ID named #myclass and give it the appropriate properties, you can later add the ID to your code and have it referenced in JavaScript as follows: <head> <script> function alertme() { window.alert(document.form1.mytextbox.value); } </script> <style> #mytextbox {background-color:silver;} </style> </head> <body> <form name="form1"> <input type="text" id="mytextbox" /> <input type="button" id="btnSubmit" value="Click Me" onClick="alertme()" /> </form>