Camera, is a device that records images that can be stored directly, transmitted to another location, or both.
Lens, positioned in front of the camera's opening to gather the incoming light and focus all or part of the image on the recording surface. 
Lens cover, covers and protects the lens during storage.
Rangefinder cameras, allow the distance to objects to be measured by means of a coupled parallax unit on top of the camera, allowing the focus to be set with accuracy.

Aperture, generally consists of an enclosed hollow with an opening (aperture) at one end for light to enter, and a recording or viewing surface for capturing the light at the other end.
Shutter, a mechanical device for opening and closing the aperture of a camera lens to expose film or the like.
Exposure, the act of exposing a photographic film or plate to light, X-rays.
Depth of field,

the range of distances along the axis of an optical instrument, usually a camera lens, through which an object will produce a relatively distinct image and much more clear.

F-stop, any of the settings for the f-number of a camera.

Focal length, The distance between the focal point of a lens (that is, the point at which the lens will focus parallel rays of light) and the lens itself.

Back part of Canon Rebel T3, The buttons that feature on the back of this camera are the zoom in/zoom out. The delete button, The menu button, The setting button, and the display button.

Top part of Canon Rebel T3, The buttons that feature on the back of this camera are the on/off button. The shutter button, The camera wheel including different features you can do to change the picture, The lens measurement and the on and off stabilizer.