JavaScript/DHTML

When people talk about client-side code or programming, they usually mean JavaScript. JavaScript is a fairly simple programming language that you can type directly into your HTML pages. You can use it to check that someone has filled out a form correctly, or open or resize new browser windows. The D in DHTML stands for Dynamic. DHTML is just a way of describing the combination of normal HTML, JavaScript and Style Sheets to control the appearance of web pages. The most common DHTML trick you will see is the 'rollover', where the web page author attaches some JavaScript to the images on a page so they change when you roll your mouse over them. Although you can't do anything useful on the server with JavaScript, you can do some pretty cool visual tricks and make some nice enhancements to your web pages.