Cameras may come in a lot of different shapes and sizes but the basic function of all cameras are the same. Shutter speed, aperture, and depth of field are universal concepts of photography. Even one time use cameras work on these three ideas. The only difference in these three concepts between types of cameras is the degree to which you can control these functions.
Aperture describes the size of an opening within the camera lens that allows light to pass through the lens. The aperture works with the shutter speed to control the amount of light striking the film or digital sensor. Aperture is generally measured byF-Stop. Aperture also has a secondary effect of controlling the depth of field of an image.
Depth of field describes how much of an image is in focus from front to back. Depth of field is controlled by the aperture as well as the lens magnification. Some images, such as portraits, have traditionally used mostly small depth of field in order to blur the background. Other images, such as landscapes, traditionally use much larger depth of field in order for the entire vista to be in focus.