The Major 7th. A Major 7 chord is built with the 1st, 3rd, 5th and 7th degrees of a major scale.
At this point, I want to begin introducing chord formulas. The formula for our Major 7 chord is: 1 3 5 7. These numbers are referring to degrees of the major scale.
Learning formulas in this manner (assuming we have a good knowledge of major scales) will eventually give you the ability to instantly create and play absolutely any chord. This skill also leads us to making wise choices when improvising over chords.
No matter what the chord or key, if you understand the formula, it makes playing the right scales or notes in your solo so much easier.