This Google Map calculates an approximate of the shortest distance between any two points on the globe. It is calculated whenever you hit the Calculate Distance button, or when you drag a marker to a different position. To create a marker, single click the map once. To remove a marker, single click the marker you want to remove. Remember that the route will not necessarily connect where you expect, if the two points you select are too far apart the route will go the opposite way of what you were expecting!