Whether we realize it or not, we all use maps every day. Global Positioning Systems (GPS) guide our trips, Doppler radar maps forecast the weather, and bus routes let us know where our stop is. A map is a bridge to another part of the world, helping us to visualize where we've been, where we are, and where we're going.

Cartography--the science of making maps--has been practiced for centuries but has advanced dramatically over the last fifty years. Not only have we mapped every square mile of land on Earth, but we've also created maps of the stars, the moon and Mars, and even the deepest oceans. Most cartographers work really hard to make their maps accurate, detailed, specific, and clear. They also tend to focus each map on a specific purpose, and this purpose affects its form.  For example, a hiking trail map may include land elevations but probably wouldn't include information about historical wars in the area. Likewise, a map of the territory explored by Marco Polo wouldn't need to show modern freeways and train tracks.

Human beings have always been driven to explore the world, and maps are the story of our discoveries. Maps help us understand how places, people, and events are interconnected, and bring the great moments of history down to Earth.