Before compass was invented, most people identified direction at Oceans only depending upon the position of the sun and stars. If it was cloudy or rainy, people would lose. It was the compass, invented by Chinese, thus solved this problem.

Compass is the instrument used for indicating direction. As early as the Warring States Period (475 BC - 221 BC), Chinese discovered that a magnet could be applied to indicate the south or the north, and a direction-indicator instrument sinan was made on the basis of this feature. The instrument comprised a smooth magnetic spoon and a copper plate carved with direction marks; the handle of the spoon point to south, and the head would point to north. In Song Dynasty, people combined an artificially magnetized compass with an azimuth plate to create a proper compass called luopan, which, in any cases, could tell sailors the accurate direction.

In Northern Song Dynasty (960 - 1127), compass was being applied to navigation. In Southern Song Dynasty, the instrument was introduced to Europe via Arabia, and Arabs at that time called it affectionately "the Eyes of Sailor".

The invention of compass had an epoch-making influence on navigation, thereby opening up a new era in the history of international navigation. Zheng He's fleets made seven voyages across seas to Southern Asia and around Indian Ocean in early Ming Dynasty, Christopher Columbus discovered the New World and Ferdinand Magellan sailed round the world in the 15th century, which was the consequence of the application of compass to the navigation.