I have used <Alt>+<Tab> for years as the shortcut to quickly switch between open application windows on my computer. As I work on a lot at once, this is a very handy friend to have around.
Frustrated that this does not help me switch between tabs in the newest version of Internet Explorer, I finally went to work to find how to do this, and located the answer I have been yearning for at Online Tech Tips.
The shortcut? <Ctrl>+<Tab>
Yes, it it that simple! Use <Ctrl>+<Tab> to switch between open tabs in Internet Explorer and Firefox, and then <Alt>+<Tab> to switch between open programs.