The amount of light collected by the sensor in your camera during a single picture. If the shot is exposed too long, the photograph will be washed out. If the shot is exposed too short, the photograph will appear too dark. Almost all cameras today have light meters which measure the light in the given shot and set the ideal exposure automatically.
The unit of measurement that defines the size of opening in the lens that can be adjusted to control the amount of light reaching the film or digital sensor.The size of the aperture can be measured in the F-stop.
Known as "exposure time" , stands for the length of time a camera shutter is open to expose light into the camera sensor. If the shutter speed is fast, it can help to freeze action completely. If the shutter speed is low, it can create an effect called "motion blur" where moving object appear blurred along the direction of the motion.
A way of guiding of the viewer's eyes towards the most important element of your work. A good composition can help you make a masterpiece even out of the dullest objects and subjects in the plainest of environment. A bad composition can ruin the photograph completely, despite how interesting the subject may be.
RULE OF THIRDS
Photo are divided into thirds with two imaginary lines vertically and two lines horizontally making three columns , three rows and nine sections in the images. Important com-positional elements and leading lines are places on or near the imaginary lines and where the lines are intersect.
DEPTH OF FIELD
The amount of distance between the nearest and farthest object that appear in acceptably sharp focus in the photograph. A preferred selection Depth Of Field (DOF) in a focused subject in an image can be quite subjective.
The basis of every composition , it determines whether the photo is pleasing and harmonious or uncomfortable and unresolved to look at. Take balance in its lateral sense and the analogy of weighing scales comes in to mind.