A digital watch display is the easiest way to tell time because it literally tells you. The display of time is in digital numbers, versus the analog display with hands. Digital watches work by electrical structures powering the number/digit display. Most commonly, digital watches display time in a 24-hour format. However, there are many digital watches that allow you to set the format according to your format. Digital watches display time in a 24-hour format, versus a 12-hour format on an analog display. Digital watches typically either run on a power supply or batteries that you can replace.