Exploration, a search that enlarges knowledge of the world, the solar system, or the universe. Although exploration is as old as humanity itself, the map of the world still contained large blank spots as recently as the 1870's. Even today many places on the earth still have not been systematically explored. With the coming of space travel, exploration seems barely to have begun.

There are many practical reasons for exploration---to find new sources of raw materials, new trade routes, or better living conditions; to win great wealth; to gain a military advantage over an enemy; to spread religion; or to add to scientific knowledge. Often none of these reasons fully explains why explorers are willing to brave the hardships they must face---unfriendly oceans, mountains, jungles, and deserts; extremes of heat and cold; hunger and loneliness. Behind the practical reasons there lies a motivation so strong that it is irresistible---curiosity, the spirit of adventure, the challenge of the unknown.

An explorer's discoveries will leave a mark on civilization only if others understand and accept them. Otherwise the explorer is little more than a voyager, or traveler. The Vikings provide a good example. They are believed to have been the first Europeans to reach America, about 1000 A.D. At that time, Europe was not interested in a new world, and nothing came of the Viking discoveries. When Christopher Columbus landed in America 500 years later, Europe was ready to expand its horizons through exploration and colonization.

The progress of exploration is closely related to the development of transportation. Early peoples could explore only as far as their feet could carry them. The development of land, sea, and eventually, air transportation permitted exploration of the entire world. Then rockets expanded exploration beyond the limits of the earth.

Explorers have made possible the spread of civilization. They have linked together the people of the world so that each may benefit from the accomplishments of the others. One of the most far-reaching results of exploration was the opening of America for colonization. New sources of raw materials discovered by explorers have resulted in new industries and higher living standards.