The second aspect of the f/stop or aperture is more about creative control. Though the camera will focus on the subject to make it clear, the aperture controls what else in the entire scene will be clear or blurred-out. A low number f/stop will blur the foreground and background. As the f/stop number increases, the amount of clarity before and after your subject will increase as well. In photography, this amount of clarity is referred to as depth-of-field. Low number f/stops will blur the background, (shallow depth-of-field.) Maximum depth-of-field is achieved at the highest f/stop number of your camera. All the f/stops between the minimum and maximum will give you varying degrees of clarity throughout your photograph.
Keep in mind that changing the f/stop will control the amount of light through the lens and the amount of depth-of-field at the same time. Low number f/stops let in more light and have shallow depth-of-field. Higher f/stop numbers let in less light and have more depth-of-field.
The aperture is one half of how your camera takes a picture. Be on the look-out for the next installment in this educational series: The Shutter Speed!