The Camera

A camera is a device that records images that can be stored directly, transmitted to another location, or both. These images may be still photographs or moving images such as videos or movies. The term camera comes from the word camera obscura (Latin for "dark chamber"), an early mechanism for projecting images. The modern camera evolved from the camera obscura.

Aperture  is a hole or an opening through whichlight travels. 

Shutter  is a device that allows light to pass for a determined period of time, for the purpose of exposing photographic film or a light-sensitive electronic sensor to light to capture a permanent image of a scene. 

exposure is the amount of light allowed to fall on each area unit of a photographic medium (photographic film or image sensor) during the process of taking a photograph. 

depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. 

f-stop number is a ratio of the focal length of the lens to the diameter of the aperture. A lens is said to be "wide open" when it's set on its smallest f-stop, or with the aperture opened as wide as possible.

focal length of an optical system is a measure of how strongly the system converges or diverges light.