Pixels: a minute area of illumination on a display screen, one of many from which an image is composed.
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:which stands for Photoshop Document, is 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 time for which a shutter is open at a given setting.
Depth of Field:the distance between the nearest and the furthest objects that give an image judged to be in focus in a camera.
Bitmap:a representation in which each item corresponds to one or more bits of information, especially the information used to control the display of a computer screen.
Exposure:the state of being exposed to contact with something.
Watermarking:mark with a watermark.
Optical Zoom:is a true zoom feature. It allows you to zoom in (or out) on the subject in the LCD or viewfinder. 
Digital Zoom: is a software feature that uses one of two methods: 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 Stablelizing: is a family of techniques used to reduce blurring associated with the motion of a camera or other imaging device during exposure.
Noise:a sound, especially one that is loud or unpleasant or that causes disturbance.
Lag Time: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:relating to or used in macrophotography
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:  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.