Tourism differs from travel as leisure differs from labor.
People travel for any number of reasons, from business to war or religion.
Tourism, however, is travel undertaken for pleasure. Depending on individual tastes, it may involve rest and relaxation, sports, cultural exchanges, educational and aesthetic experiences, or eating and shopping. As a modern multimillion-dollar business, it caters to the tourist's need for transportation, accommodation, food, entertainment, recreation, health, souvenirs, and social contact. Mass tourism is a relatively modern phenomenon, but travelers have reacted as tourists, regardless of the purpose of their journeys, since the beginning of recorded history. To write his history of the war between the Greeks and the Persians, Herodotus personally visited many of the areas making up the Persian Empire.