How to screenshot in mac os x

To take a screenshot of the whole screen, press cmd+shift+3. To take a screenshot of a custom size, press cmd+shift+4 and proceed.

When your cursor changes to this, hold and drag to screenshot the selected screen area. To take screenshot of a whole window, press space and proceed.

When your cursor change to this, put it on a window and click to screenshot that particular window. Before the shot, you can press space again to get back to custom size screenshot.

The result .png file will appear on the desktop.