The word photography means "writing with light". Light is essential to making photographs and you must understand how to use it in order to make your pictures as interesting as possible. There are two basic types of light: natural and artificial. The first comes from the sun, the other from man-made sources.
Natural light generally reiterates to daylight, although moonlight qualifies too. For photographers, light during the day can vary. There might be a bright or hazy sun that causes shadows. Or it could be heavy and overcast. Daylight also exists in the shade, where subjects are shielded from the direct rays of the sun. Daylight exists indoors, too so not all natural light shots are taken outdoors.
Artificial light is illumination produced by man. It may be an ordinary light bulb, a fluorescent tube, a bright photoflood, a tungsten halogen lamp, an electronic flash, or many other types. Since these types of illumination can be used outdoors, too, not all photographs shot with artificial light are taken indoors.
Photographers also talk about ambient light, existing light and available light. Regardless of the term, this is light – whether natural or artificial- that is already present in the subject area. A photographer who shoots by ambient, existing, or available does not provide any of his own illumination.
Just as there are types of light, there are types of lighting that have special significance for photographers. For instance, directional lighting, such as that provided by the sun, flash, or tungsten halogen bulbs in reflectors, is more precisely described as being front lighting, side lighting, or back lighting.
Front lighting is the most basic for photographers, although not the most appealing. A long-standing rule that says to put the sun at your back so it shines on the front of your subjects was established for good reasons. Early films and camera lenses were not as fast as those in use today; they required considerable light to make an exposure. Old time camera and film manufacturers knew that bright and direct sunlight on the subject would provide an adequate image on the film, so they recommended it. Also, a subject illuminated directly from the front shows every detail because it is uniformly lighted.
Front lighting is still popular today, but many photographers find it unsatisfactory for portraits and other subjects. The reason is that front-illuminated subjects appear 'flat' because there are no shadows to give a feeling of depth. For this reason, front lighting is commonly referred to as flat lighting. Another disadvantage of front lighting is that people often squint because the sun is shining directly in their eyes.
Photographers have found that changing their camera angle or the position of the subject so that the main illumination is from the side gives more depth and interest to many of their pictures. This is especially true when shooting close-ups of objects. Side lighting can illuminate the left side or the right side of the subject, depending on your preference.
Backlighting reiter to situations where the main source of illumination is behind the subject, shining in the direction of the camera. Backlighting requires careful exposure readings so that the front of the subject will be properly exposed. If a reading is made of the backlight itself, the subject will be underexposed and appear as a silhouette. With portraits outdoors, backlighting allows your subject to have a natural expression without squinting because bright light is not shining on his face or into his eyes.
When strong directional light comes from both sides, the technique is known as cross lighting. It is normally used in studio situations with flash or tungsten studio lights, not under daylight conditions.