The term “low-key” refer to any scene with a high lighting ratio, e.g. 8:1, especially if there are high proportions of shadowed areas.
In Low-Key images the tone is darker with a great deal of contrast, usually creating large black fields in the photo. It is very common for Low-Key images to give special attention to contour lines, emphasizing them with highlights. Most notable is a light surrounding the subject illuminating only the outline of a subject known as rim light.
Low-key lighting requires only one key light, with an optional fill light or a simple reflector.
Low-Key images are darker and present drama or tension.