Laughter is described as the physical reaction that humans have which can contain rhythmic contractions of the respiratory system and our diaphragm. It can happen because of some kind of stimulation, whether internal or external. However, laughter is much more than the definition you can find on Google or Wikipedia. Laughter has been referred to as "the best medicine" for centuries. It may not be the only medicine, but it is the indisputably "best medicine" for any human being. Nobody knows who first coined that statement; but it's been around for ages.