The magnetic compass consists of a magneti pointer (usually marked on the North end) free to align itself with Earth's magnetic field. A compass is any magnetically sensitive device capable of indicating the direction of the magnetic north of a planet's magnetosphere. The face of the compass generally highlights the cardinal points of north| south| east and west. Often| compasses are built as a stand alone sealed instrument with a magneti bar or needle turning freely upon a pivot| or moving in a fluid| thus able to point in a northerly and southerly direction.
The compass greatly improved the safety and efficiency of travel| especially ocean travel. A compass can be used to calculate heading| used with a sextant to calculate latitude| and with a marine chronometer to calculate longitude. It thus provides a much improved navigational capability that has only been recently supplanted by modern devices such as the Global Positioning System (GPS).