A stacked bob is a short haircut in which the hair is usually cut straight around the head at jaw level, layered and styled with a fringe. A stacked bob increases the volume of hair at the crown of the head.
The haircut is a variety of the bob, which includes both shorter and longer styles such as the Chinese bob, A-line bob, shingle bob and shoulder-length bob. The length varies according to the size of the face and thickness of the hair. According to Wikipedia, the bob has been around in the west since at least the beginning of the 20th century and has enjoyed several periods of popularity thanks to celebrities who wore the style. Although the bob is mainly worn by women, sometimes men also opt for the style.