Rotational symmetry in capital letters describes a property in which the letter looks the same after being rotated. Capital letters that have rotational symmetry are: Z, S, H, N and O.
The letters Z, S, H and N, when rotated 180 degrees clockwise or counterclockwise, will look the same after rotation completion. This is called rotational symmetry on the order of two, because there were two 90 degree rotations. The letter O has rotational symmetry on the order of one, because after being rotated by 90 degrees, it still looks the same.
Letters can also have lines of symmetry, either vertically or horizontally. Examples of letters with a vertical line of symmetry include: A, H, I, M, O, T, U, V, W, X and Y. Examples of letters with a horizontal line of symmetry include B, C, D, E, H, I, K, O, S and X.