Since the time mankind ceased nomadic existence and took up fixed habitations, land and buildings thereon and interests therein have been the subject of commercial transactions. Large areas of the earth's surface are now privately owned, improved in many cases with very valuable buildings and in populous communities the land represents a large part of the wealth of the community. It is bought and sold, improved, managed and variously dealt in constantly. This has given rise to the real estate business which engages the attention of many persons; from the man who buys a home only a few times during his life, to the man whose entire time is devoted to the business either for himself or others.