Windows can make your basement more aesthetically pleasing and improve safety. Large basement windows, sometimes called "egress windows," from Pella of Natick are made to allow more light into underground spaces than the older, smaller, rectangular windows that are added above ground. They also give you a way out in case of an emergency.
The main differentiator between basement, or egress, windows and standard windows is that basement windows have to be big enough for an average-sized person to get out in order to meet safety requirements outlined in building codes. You can choose from properly sized casement, sliding or double-hung windows when you install basement windows. Make sure you fully understand local building codes before your purchase of basement windows.