If you have Windows 7 installed in your computer, you probably are wondering where the good old "Show Desktop" icon is. It actually did not disappear, just replaced by a button that ordinary users can hardly notice.
You may have looked for terms such as Get the Old "Show Desktop" Back in Windows 7, How to Show Desktop in Windows 7 (Quick Launch Alternative), How to really pin the Show Desktop to Taskbar in Windows 7, or Has Microsoft Removed Show Desktop Shortcut in Windows 7 in search engines and haven't found the answer.
If you aren't observant enough, you will just think that the new "Show Desktop" button is a plain taskbar design or, to say the least, won't mind it at all.
The following image will show where it is.
It isn't hidden; the button just sits there at the farthest right of the Windows 7 superbar. Click it and all the open windows will be minimized thus showing your desktop.