A degree is the everyday way to measure an angle. A full turn is split into 360 equal degrees, so a quarter turn is 90 degrees and a half turn is 180 degrees. The number 360 comes from ancient Babylonian astronomers, who counted in sixties and liked that 360 divides evenly so many ways.

You meet degrees whenever direction or turning matters: a compass bearing, the slope of a roof, the angle of a camera lens, or the corner of a triangle. Each degree can be split further into 60 minutes, and each minute into 60 seconds, which is how map coordinates get their fine detail.

In writing, the degree is usually shortened to "°". One degree is 1 degrees, and that ratio is what every number on this page is built from.