The Camera

Vocabulary:

Lens- Position in front of the camera's opening to gather the incoming light and focus all or parts of the image on the recording surface.
System Cameras- Interchangeable parts and allowing customization.
Focal-Plane Shutter- Located in front of the film plane, prevents the light from reaching the film even if the lens is removed.
Autofocus- Optical system uses a sensor, a control system and a motor to focus fully automatic or on a manually selected point or area.
Aperture- An enclosed hollow with an opening at one end for light to enter.
Shutter- A devise that allows light to  pass for a determined period of time.
Exposure- The amount of light allowed.
Depth of Field- The distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.
F-Stop- The ratio of the lens's focal length to the diameter of the entrance pupil.
Focal Length- Measure of how strongly the system converges or diverges light.

Buttons:

AE/FE lock button that seconds as the index key when in Playback mode, and next to that is the AF point selection button that seconds as the magnify button when in Playback. Underneath of these two buttons is the small speaker for audio playback.

AV/Exposure compensation button, which allows you to switch between shutter speed and aperture values in Manual mode, or exposure compensation in Program mode. 

Live View/Movie shooting button. Pressing this button will enter Live View mode when in a still image mode, or will Start/Stop video recording when the mode dial is set to Movie mode. 

Quick Control button for the T3's shortcut menu, which is also used to access the Direct Print function while in Playback mode.

DISPlay button, which controls the amount of information shown on the LCD screen. 

4-way controller, which has several jobsThese include navigating the menu system, scrolling inside an enlarged image in playback mode, and a quick recall of specific camera functions. Pressing "Up" will display the ISO settings, "Right" accesses the AF mode, "Down" gives access to the White Balance modes, and "Left" toggles the drive mode (burst/self-timer). Lastly we have the Menu and Play buttons at the bottom.