Compass is a simple instrument that has a magnetic needle that can rotate
freely in one plane and it points North-South when compass is in
horizontal position. It is used for navigation and orientation. People
knew about magnet and how it affected iron 600 years before it was used
for the first time as a compass. Even then it was not used for navigation
but for geomancy. 900 years later it was used in astronomy and for
orientation and for same purposes is used still.
Learn more about the history of compass