Aperture – The lens opening. The opening in your camera lens that lets light pass into the camera. Aperture size is usually noted in f-numbers; the larger the number, the smaller the lens opening.
Aperture Priority – An exposure mode on an automatic camera that lets you set the aperture while the camera sets the shutter speed for a proper exposure. If you change the aperture, or the surrounding light level changes, the shutter speed will change automatically.
Autofocus (AF) – A system by which the camera lens automatically focuses your image.
Background – The part of the image that appears behind your main subject.
Bracketing – Taking additional pictures of your subject with a range of exposures (lighter and darker) when you are unsure of the correct exposure.
Bulb (B) Setting – A shutter-speed setting on an adjustable camera that allows you to time your exposures. When using bulb mode the shutter will stay open as long as you hold the shutter release button.
Candid Pictures – Un-posed photos of people, often taken without the subject’s knowledge. These images appear more natural and relaxed than posed photos.
Composition – The arrangement of elements within an image. Includes the main subject, the foreground and background, as well as any supporting subjects.
Depth of Field – The amount of distance between the nearest and farthest objects that appear in acceptable sharp focus in a photo. Depth of field depends on the lens opening, the focal length of the lens, and the distance from the lens to the subject and the subject to the background.
Exposure – The amount of light allowed to enter your camera to create the image. Too much light and you are overexposed; too little and you are underexposed.
Foreground – The area between the camera and your main subject.
Front lighting – Light shining on the side of your subject which faces the camera.
Hot Shoe – The mount on a camera that holds an external flash unit.
Panning – Moving the camera so that the image of a moving object remains in the same relative position in the viewfinder as you take a picture. Panning creates a sence of motion.
Shutter – The movable cover in a camera that controls the time during which light reaches the sensor.
Shutter Priority – An exposure mode on an automatic camera that lets you select the desired shutter speed; the camera sets the aperture for proper exposure. If you change the shutter speed, or the light level changes, the camera adjusts the aperture automatically.
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Feel free to add more photographic terms in the comments! We can all learn from each other.