Aperture

Aperture: size of the lens opening that lets light into the camera.

Aperture= f-stops

When you open or close a lens aperture, you double or halve the area through which light can travel.

The smaller the f-stop the larger the hole (or space for light to travel)

If you have the f-stop f/2 you will let in a whole lot of light.

If exposure is made with a wide aperture (small f-stop) the objects further away from the subject are thrown further out of focus. This is called depth of field.