Aperture is used to control the depth of field of an image and it is known as 'f-stops’ on DSLR cameras. Aperture is commonly used to control the blurriness of an image, this allows the photographer to have a blurry background while having the subject in focus. At the same time, the aperture also control the amount of light from reaching the camera’s image sensor. Examples of ‘F-stop numbers’ as seen on all DSLR cameras are f/1.4, f/2, f/2.8, f/4, f/5.6, etc. In different camera lens, the ‘f-stops’ can be varied depending on the type of lens. Prime lens tends to have lower ‘f-stop’ numbers while Macro lens tends to have a higher ‘f-stop’ numbers.
Large aperture = Small f-number = Shallow (small) depth of field
Small aperture = Larger f-number = Deeper (larger) depth of field