Aperture & Shutterspeed

Aperture:

 Aperture is a hole within a lens, that light uses to enter the camera body.  If you were to reduce the aperture, say to F2, making the hole bigger and a shallower depth of field the shutter speed has to decrease to keep the exposure the same.When the shutter speed decreases, the chance of subject blur increases.

Faster shutter speed, lower aperture, larger opening, shallow DOFSlower shutter speed, higher # aperture, smaller opening, larger DOF

 

larger opening, faster shutter speed   >   >    >   >   >    >  smaller opening, slower shutter speed

So these three photos demonstrate the process of depth of field increasing and the relationship between aperture and shutter speed. The amount of light you let in directly correlates to the amount of time you have to set the exposure at. If you want a larger depth of field, your aperture has  to be higher, and the result of that, for a decent exposure for this picture, the shutter speed had to be slower to let in light for a longer amount of time due to the smaller opening.
Shutter Speed:
Slower shutter speeds allow more light to be let into the camera and is used for low-light photography, while fast shutter speeds help to freeze motion. Shutter speed is easier to understand conceptually, but it still corresponds with aperture, so for a correct exposure, the two need to work together.