The notes of the C Ionian or C Major scale are C, D, E, F, G, A, B, C’ and you get them by playing upwards from C to C’ on the white notes of a piano, or if, in tonic solfa, you sing the familiar scale of “do, re, mi, fa, so, la, ti, do”. Note the distribution of tone and semitone intervals in this scale:
The Ionian (or the familiar do, re me) scale is the most important scale in most types and genres of Western music. Bertrand Bronson writes:
The Ionian scale …has been from time immemorial designated as the mode of popular song—the modus lascivus of ecclesiastical execration—and …in bulk, it is by far the predominating mode in the extant folksong record—at least in British-American tradition. (Bronson, Bertrand H., “Folksong and the Modes,” The Musical Quarterly, Vol. 32, No. 1 (Jan., 1946), pp. 37-49. The quotation is from p. 43.)
Likewise, Frank Purslow remarks that the majority of the tunes collected by George Gardiner (65 percent, or a total of 755) are Ionian; indeed, Purslow ridicules the obsession that he claims to discern, among the great collectors of the early twentieth century, with tunes in the other 3 modes:
To say …that these modes are the modes of English folk song is absolute nonsense. The English peasant has always preferred to sing in the Ionian mode. (Purslow, Frank, “The George Gardiner Folk Song Collection,” Folk Music Journal, 1967, pp. 129-157. The quotations are from pp. 133-5.)
Purslow’s claim that Gardiner’s non-Ionian tunes are attributable to Irish influence is contestable and problematic, but his main claim would seem to be true. The Ionian scale has been the dominant scale of Western music. Glarean noted its preponderance way back in the sixteenth century, and it is dominant in classical and art music. Some of our most characteristic, iconic and beautiful folk melodies are Ionian. Below you will find a sample of them.
03 The Knight and the Shepherd's Daughter (Cecil J. Sharp, 1916, One Hundred English Folk Songs)
Tune Analysis: G Ionian, Heptatonic, Plagal
Cruel Father and Affectionate Lovers Version 1 of 3 (GB/6a/56)
Tune Analysis: G Ionian, Heptatonic, Plagal.