Why is a feather shaped like a feather?

Answer 1

Feathers are a marvel of nature. Since there isn't just one shape for a feather, the question should be re-phrased to inquire about common traits of feathers and why they are shaped like a wing.

Many feathers make up a wing. Feathers have their shape to make a wing. Wings are designed much like an airplane wing. The front blade of the wing is shaped so an air foil occurs over the top of the wing. When air accelerates, pressure drops. This creates a differential in pressure between the top and bottom of the wing. Since air pressure moves from high to low, the low pressure created by air accelerating over the top of the wing creates lift under the wing.

If you look at an individual feather, you will see that the shape imitates that of a wing. The multiple shapes of feathers can then be defined based upon their location on the wing and their shape variations based upon flight performance and aerodynamics.