Final answer:
The key light placed to one side of the subject is known as side lighting. This technique is used to create a more three-dimensional appearance by casting shadows on the side opposite the light, adding depth and drama to the photo.
Step-by-step explanation:
If a key light is placed to one side of the camera/subject, it is known as side lighting. This type of lighting creates a three-dimensional effect in a photograph by casting shadows on the side of the subject opposite the light source. Side lighting highlights textures and shapes, giving the photo a more dynamic and dramatic look compared to other lighting directions, such as front lighting where shadows are minimized, back lighting that can create a silhouette effect, or top lighting which can cast shadows downward and may emphasize certain features differently.
Photographers use side lighting to control the mood and depth of their images, bringing attention to specific details and creating a sense of volume. When shooting portraits with side lighting, the photographer must consider how to balance the light and shadows to achieve the desired effect, which may involve using fill flash or reflectors to soften harsh shadows.