As a web developer, I’m often forced to support for outdated browsers like Internet Explorer 7. This requirement forces my hand to add wonky code to code that was otherwise working fine everywhere else. To help test my sites in multiple versions of Internet Explorer, I use Internet Explorer 9 on Windows 7 and use the Developer Tools to change the rendering mode of the page between IE 7, 8, and 9. It’s important to note that this is not an exact representation of what a user with Internet Explorer 7 would see on the page, but it is accurate enough for me.
Here’s Microsoft’s official tech docs about this property: