In the Western music tradition, pitches are named after the first seven letters of the alphabet, A, B, C, D, E, F, and G.
D, [ré] E, [mi] F, [fa] et G [sol]. Après ça, le cycle se répète : A, [la] B, [si] C, [do] D, [ré] E, [mi] F, [fa] G [sol], A, [la] B, [si] C, [do] D, [ré] E, [mi] F, [fa] G [sol], et ainsi de suite.