The english alphabet. It consists of 24 letters and is taught in most counties. It has it's own song that has the tune of "Twinkle, Twinkle Little Star". It is used in every word of this definition too.
"A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, and Z. Now I know my ABC's Next time won't you sing with me?" That was the song abcdefghijklmnopqrstuvwxyz.