Why are the orbitals shells called s, p, d, f, etc.? is there a reason?

The letter refers to the shape of the orbital. The letters go in the order s, p, d, f, g, h, i, j, etc. The letters s, p, d, and f were assigned for historical reasons that need not concern us. All we have to do is remember the shapes that correspond to each letter.

hope this helps!