Removing the background of an image.

[Ofnuts]

The "weird squares" are not part of the image, they are just an indication of where the image is transparent. Another way to see it is that the checkerboard pattern is a permanent background image. You see it where you image is transparent. But it isn't saved with you image (but since many image viewers display transparency that way, somtime you can be led to believe that it iis part of your image).