However, we would like to be able to raise the plane up into the air - and we call that lift . Also, unless you push really hard on it, the plane is sitting still on the ground because of the friction between the wheels and the ground. When the plane starts rolling there will be friction between the air and the plane - and we call that drag . So, to make the airplane fly somewhere, we have to do at least two things. What you build to satisfy the requirements are called the structures or the components .
Birds provide the thrust and lift from their wings when they flap and soar.
The first attempts at making an airplane were devices that flapped huge structural wings like a bird. These planes didn't fly too well. Airplanes and birds both fly, but they do it in different ways. It is often useful for engineers and other types of designers to think of the functions or the requirements of something before thinking of the form . In the case of designing airplanes - thinking about the form first got engineers stuck in a rut of making machines that flapped like birds.