Internet Explorer's version number always appears in its About dialog box, but the method to reach that box varies depending on which Internet Explorer interface you're using. For the default, desktop interface, you can find it in the Tools or Help menu. In the Windows 8 app interface, you reach it through the Charms bar.
Internet Explorer Desktop Program
Open the Tools menu, represented by a gear icon, and click About Internet Explorer to find the version number on any version since Internet Explorer 9.
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Open the Help menu and click About Internet Explorer if you don't see the Tools menu icon. This method works both on Internet Explorer versions prior to 9, and on later versions if you have the menu bar enabled.
Read the major version number alongside the Internet Explorer logo, and check the Version line if you need to know the exact edition of the program.
Windows 8 Internet Explorer App
Press Windows-C while in the Internet Explorer app to open the Charms bar. Click or tap Settings.
Select About in the Settings menu.
Read the version number in the About box. Usually, you'll only need to know the major version number for Internet Explorer, such as 10 or 11, which appears before the first decimal.
Your version of Windows doesn't directly affect your version of Internet Explorer -- IE 11 on Windows 7 works just like the desktop interface for IE 11 on Windows 8. Windows versions can have a maximum Internet Explorer version, however: Windows Vista can't update past IE 9.
Running an outdated browser can pose a security risk, so update to the latest version supported by your operating system whenever possible.