Most people do not realise that Internet Explorer is embedded within the Windows operating system as the web core. This web core is used by other applications (basically any apps that use HTML, such as iTunes) to display web content. It’s also used for HTML-based help.
However, this also means that this same web core (the Internet Explorer web engine) could be used….within another web browser. Indeed they do, Maxthon, Avant and others are an extensive wrapper around the existing IE core. But, what happens if someone went one step further and enabled you to view IE content within Firefox. This would be ideal for web developers who wanted to see how their web page appears within Firefox and Internet Explorer, without having to use Internet Explorer. If you’re a regular web user, you might stumble across a web page that appears irregular within Firefox and you need Internet Explorer to view the page correctly.
IE Tab is an extension for Firefox that enables you to view Internet Explorer content within Firefox, in its own tab.
Note that this will only work with the Windows version of Firefox.