How does GPS accurately pinpoint your location anywhere?

GPS works like having four special friends who tell you exactly where you are by using time and distance.

Imagine you're playing hide-and-seek in a big park. You count to ten, and then your friends start shouting out how far they think you are from them, one says “you’re 10 steps away from me,” another says “you’re 20 steps away from me.” With each shout, you get closer to figuring out where you're hiding.

GPS does something similar with satellites in space. Each satellite sends a signal that says, “I sent this message at exactly 1:00:00 PM!” Your phone listens and says, “I received it at 1:00:02 PM.” That means the signal took 2 seconds to reach you, and since we know how fast signals travel (300,000 km/s), your phone can figure out how far away that satellite is.

By getting messages from four satellites, your phone solves a puzzle. It knows how far it is from four different places in the sky, like having four friends telling you how far you are from them, and uses that to find exactly where you are on Earth, even if you're hiding under a tree!