DC flows in one direction. It was invented by Thomas Edison and was used to power homes in the late 1800s. The drawback to this system was that the homes had to be within a one-mile radius of the generating station because electricity loses its power traveling long distances. Using a battery-operated flashlight is an example of DC power. When the light is turned on, electrons exit the battery through the negative end, travel to the bulb and back to the positive end of the battery, all flowing in one direction.
AC was discovered by Nikola Tesla. He found that it could travel long distances without losing its power, making it ideal to power homes. Since electricity is made up of negative electrons, a negative charge will repel the current while a positive charge will attract it. By constantly introducing positive and negative charges to both ends of the conductor, the current changes its direction.
AC powers our homes. Anything plugged into the wall, such as a lamp or fridge, uses this alternating current. Examples using DC are batteries and solar cells, anything where the electrical charge does not have to travel great distances.