The Major Scale

The music dictionary defines the Major Scale as:

"Diatonic Scale in which the half-steps occur between
the 3rd and 4th degrees and the 7th and 8th degrees"

Confused? How about:

The main building block of all western music theory is the Major Scale.
I suppose it's major for that reason.

The sound it creates is the famous do-re-mi best described musically in "do, a deer" from The Sound of Music. (See "Doh!, a deer")