Major Chord

The major chord has notes 1, 3 and 5 of the major scale.

Or you can say the interval from the low note to next note is a MAJOR 3rd,
while the interval from the low note to the high note is a perfect 5th.

The interval of the major 3rd is the defining note.

The song example is Jingle Bells which has it's melody centered on the major 3rd note.