Understanding the Application Compatibility Challenge
Windows Internet Explorer 8 is the default browser in the Windows 7 operating system. Internet Explorer 8 improves many features, including an enhanced platform architecture that is designed to make the web safer and faster for users and easier to configure and manage for IT professionals, and to create innovative content for web developers.
Some of these features use new rendering and scripting engines, which are the core elements that Windows Internet Explorer uses to display HTML and CSS content and run scripts. The architectural changes and platform enhancements introduce application compatibility issues that you might experience when you migrate applications to Internet Explorer 8 from a previous browser.
Internet Explorer 8 includes some backward compatibility, but there are some changes (including support for web standards support and security features) that might require you to upgrade web applications that are built for Microsoft Internet Explorer 6 or previous versions.
For more information about how to test and address compatibility issues for Internet Explorer 8, see Addressing Application Compatibility When Migrating to Internet Explorer 8 – Information for Information Technology Professionals.