Mac: Take a screenshot in different ways

In Mac OS X, there are 3 ways to take a screenshot.

1. Cmd+Shift+3 : Capture the entire screen.

2. Cmd+Shift+4 : Capture a selected area of your screen. The cursor will turn into a crosshair and you can drag around the area you want to capture.

3. Cmd+Shift+4+Spacebar : Capture a specific window or Dock or menu bar. The crosshair will turn into a little camera and highlight the window or objects you can capture. Left Click to capture.
You can use Expose shortcut to switch between windows. After you switch press alt or cmd key to get the little camera. Left Click to capture.