Testing your site in different browsers for usability and browser compatibility is really important. Besides the Versions 5 and 6 browsers, you should also test in older browsers (3 and 4) because a lot of the tricks we use to make our websites pretty (e.g., Cascading Style Sheets) and cool (e.g., Dynamic HTML) do not always work in the old browsers. Although it is relatively easy to install more than one version of Netscape on your computer, because Internet Explorer is tied in to your operating system, it is difficult—but not impossible—to install multiple versions of IE. Following is a list of browsers that you can download: