Polaris, or the North Star, is a Cepheid variable. This is a type of star whose brightness grows and dims regularly over time. Cepheid variable stars dim and brighten with such regularity that they are used to calculate interstellar distances.
Polaris is also a triple-star system that's about 430 light years away. Polaris A is a yellow supergiant that is 2500 times brighter than the Sun.
Polaris is also called the "pole star" because the other stars in the sky seem to orbit around it. Because it seems fixed in the sky, navigators have used it for centuries. It can be found at the tail end of the Little Dipper.