Definitions

pixels: a minute area of illumination on a display screen, one of many from which an image is composed.
image resolution: Image resolution is the detail an image holds
megabyte: a unit of information equal to 2²⁰ bytes or, loosely, one million bytes.
megapixel:a unit of graphic resolution equivalent to one million or (strictly) 1,048,576 (2²⁰) pixels
gigabyte:a unit of information equal to one billion (10⁹) or, strictly, 2³⁰ bytes.
jpeg:a format for compressing image files
psd:the default format that Photoshop uses for saving data
white balance:the color balance on a digital camera
histogram:a diagram consisting of rectangles whose area is proportional to the frequency of a variable and whose width is equal to the class interval
aperture:a space through which light passes in an optical or photographic instrument, especially the variable opening by which light enters a camera.
shutter speed:the length of time when the film or digital sensor inside the camera is exposed to light, also when a camera's shutter is open when taking a photograph
depth of field:amount of distance between the nearest and farthest objects that appear in acceptably sharp focus in a photograph
bitmap:mapping from some domain (for example, a range of integers) to bits, that is, values which are zero or one. It is also called a bit array or bitmap index
exposure:the state of being exposed to contact with something
watermarking:a pattern of bits inserted into a digital image, audio or video file that identifies the file's copyright information
optical zoom:allows you to zoom in (or out) on the subject in the LCD or viewfinder
digital zoom:One type of digital zoom simply "crops" the edges of the image
light meter:an instrument for measuring the intensity of light, used chiefly to show the correct exposure when taking a photograph
image stabilization:mechanism used in a still camera or video camera that stabilizes the recorded image by varying the optical path to the sensor
noise:mechanism used in a still camera or video camera that stabilizes the recorded image by varying the optical path to the sensor
lag time:the period of time between two closely related events
hot shoe:a socket on a camera with direct electrical contacts for an attached flashgun or other accessory
fisheye:a wide-angle lens with a field of vision covering up to 180°, the scale being reduced toward the edges
macro:short for macro lens
telephoto:a lens with a longer focal length than standard, giving a narrow field of view and a magnified image
wide angle:(of a lens) having a short focal length and hence a field covering a wide angle
DSLR:A digital single-lens reflex camera is a digital camera combining the optics and the mechanisms of a single-lens reflex camera with a digital imaging sensor, as opposed to photographic film