Unlike many other photography styles, the subjects of portrait photography are often non-professional models. Family portraits commemorating special occasions, such as graduations or weddings, may be professionally produced or may be vernacular and are most often intended for private viewing rather than for public exhibition.

However, many portraits are created for public display ranging from fine art portraiture, to commercial portraiture such as might be used to illustrate a company’s annual report, to promotional portraiture such a might be found on a book jacket showing the author of the book.

There are many different techniques for portrait photography. Often it is desirable to capture the subject’s eyes and face in sharp focus while allowing other less important elements to be rendered in a soft focus. At other times, portraits of individual features might be the focus of a composition such as the hands, eyes or part of the subject’s torso.

Additionally another style such as head shot has came out of the portraiture technique and had become a style on its own.

There are essentially four approaches that can be taken in photographic portraiture — the constructionist, environmental, candid and creative approaches. Each approach has been used over time for different reasons be they technical, artistic or cultural. The constructionist approach is when the photographer in their portraiture constructs an idea around the portrait — happy family, romantic couple, trustworthy executive. It is the approach used in most studio and social photography.

It is also used extensively in advertising and marketing when an idea has to be put across. The environmental approach depicts the subject in their environment be that a work, leisure, social or family one. They are often shown as doing something, a teacher in a classroom, an artist in a studio, a child in a playground. With the environmental approach more is revealed about the subject. Environmental pictures can have good historical and social significance as primary sources of information.

The candid approach is where people are photographed without their knowledge going about their daily business. Whilst this approach taken by the paparazzi is criticized and frowned upon for obvious reasons, less invasive and exploitative candid photography has given the world superb and important images of people in various situations and places over the last century. The images of Parisians by Doisneau and Cartier-Bresson to name but two, demonstrate this.

As with environmental photography, candid photography is important as a historical source of information about people. The Creative Approach is where digital manipulation (and formerly darkroom manipulation) is brought to bear to produce wonderful pictures of people. It is becoming a major form of portraiture as these techniques become more widely understood and used. [Source: wikpedia]