Aperture

f/5.6, taken inside a cab

aperture of 1.8, for more depth of field

Here are some examples of aperture settings from my D40 using the 50mm lens. Aperture is the hole or opening where light passes through. In photography, aperture refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For more detailed stuff regarding choosing the right aperture, click here. And here as well.

In cameras, low f-stops translate to greater DOF (depth of field) and more light is captured. The higher f-setting makes sharper images but decreases the amount of light being admitted.

aperture of 1.8, suitable for wedding portraits. extreme blurring of the subjects outside the focus range

aperture of 5.6, for general photography.. notice the slight blurring of the background

high apertures are ideal for landscapes, has minimum depth of field, and both foreground and background are in focus