Visual Flight Rules (most commonly heard simply as VFR) is an aviation term referring to a mode of flight. One can fly an aircraft visually - that is, referencing clouds, other aircraft, and the ground by looking out the window - or one could do the same by looking only at the instruments inside of the airplane.

Since learning how to fly IFR (Instrument Flight Rules) is expensive, (relatively) difficult, and not as scenic (your eyes are busy inside all of the time!), most new pilots choose to fly visually when given the choice.

When in Canada and the USA (and most of the world too) and flying under VFR, in most circumstances, you must stay out of Class A airspace (which is reserved for IFR only), you must be at least 1000 feet above or below cloud, and you must be at least 1000 feet away from cloud horizontally. In addition, you must always be able to see the ground! Because you are flying visually, the fact that you have a GPS system, a homing beacon, a crystal ball, DME, range finder, and who knows what else, doesn't really matter. When flying VFR you have to be able to know where you are at any given time without looking at anything inside the aircraft.

When flying VFR you must also be specially rated to fly at night, since seeing the ground at night is pretty tough. It is generally preferred to fly IFR at night.