Last month, Microsoft showed what the next version of Windows will look like on tablets.

Although it was only a canned demo, and Windows 8 won't ship until next year at the earliest, it showed that Microsoft is doing some fresh thinking about interface design.

But unless you follow the company closely, you might not realize that Windows 8 descends from a long line of other Microsoft ideas.

A lot of these were experimental products. Some never made it to market. None became popular enough to challenge the old "icons on a desktop" model that's been around since the early 1990s, and has spread from the Mac and Windows to the mobile world.

But they are all a part of Microsoft's history -- and intellectual property -- and they all contributed to the thinking behind Windows 8.

Join us as we take a look back at the Windows 8 family tree.