To some people, travelling is a great luxury, and for others, it is an essential part of their job. Therefore, a distinction should always be drawn between travelling for recreation and for commercial purposes, such as business trips, for example. Ultimately, travelling can include moving a mile or two from your home once in a while to constant globe-trotting. As such, travelling tends to be defined more by the motivation behind it. For example, travel is often conducted for trade as well as intercultural reasons. In addition, personal motivations include pleasure, relaxation and convalescence, exploration, pilgrimages, adventure and for building or maintaining personal relationships. Travel by individuals, rather than the nomadic movement of entire tribes of people, has been recorded in history since ancient times. Travel and tourism are now one of the globe's biggest service industries.