Bay windows and bow windows are designed by joining three or more windows so that they angle out from your home. Bay windows typically have three panels while a bow window usually has four or five. A bay window usually consists of a picture window with two other windows on either side while bow windows are installed in a radial formation for a rounded appearance from outside of the home. Bay and bow windows provide more interior physical space while increasing the amount of light that enters the home. They can be casement, single-hung or picture windows depending on design preference.