Ever wonder why the A train is blue on the map but the 6 train is green? Or why you never see an F train on a 2 train platform? Once you learn the method behind MTA subway colors and names, the map will never look the same.

New York City’s MTA has put out a short video that explains the color and numbering scheme for the multitude of subway lines that serve the city, which is a fascinating exercise in branding and wayfinding for a complicated system.