>>5887082DOF is how much of the picture is sharp and in focus. It is controller by how wide the aperture blades open when you take a photo.
This also effects how much light enters the lens to create the image, a large aperture of f/2.8 allows a lot of light in but will have a very shallow DOF, a small aperture like f/22 will have a wide DOF and everything will be in focus, but it will only let in a small amount of light, so you will have to compensate with a higher ISO (a digital way of increasing light sensitivity - on older or cheap cameras this looks like shit) or a slower shutter speed (this is fine as long as nothing is moving and you aren't hand holding)
