A compass works by utilizing the Earth's magnetism in order to find directions. Its invention enabled people to perform navigation over long distances, opening up the sea for exploration. The earliest compasses have been traced to the Chinese Song dynasty in the form of magnetized metal pieces floating in bowls of water.
A compass uses the rule of magnetism to determine direction. As opposites attract, the magnetized piece of the compass' southern end is attracted to the Earth's North Pole.
Navigating the sea before the compass required using the stars and land masses to find direction. In Ancient Rome, the conditions of the sea between mid-November to mid-March were considered too rough for sailing.
In the 14th century, the first compass made its debut in China. In Europe, it made an appearance in Italy. For the Europeans, the advent of the compass meant exploring and conquering new worlds.
The Spanish moved into South America, conquering a swath of land that would bring them precious metals and supplies for centuries. The Dutch, English and Portuguese all developed significant foreign territories as well.
The compass also made charting the Earth's equator and its poles a matter of plotting points using the Earth's magnetism. In addition to navigation, magnetism revolutionized the field of medicine.