Do you know how some birds have really big feathers sticking out of their tails? Well, some cars also have big things sticking out of their backs called tailfins!
Tailfins were really popular back in the 1950s and 1960s when people thought they looked really cool. They are usually made of metal or plastic and are shaped like triangles or wings. They stick out from the side of the car like airplane wings, and some are so big that they go all the way up to the roof!
Nowadays, cars don't have tailfins as often because people don't think they look as cool anymore. But sometimes, cars still have them as a way to make them stand out or for racing.
So the next time you see a car with a big triangle thing sticking out of its back, you can tell your friends that it's called a tailfin!