[MUSIC] Up until now, we have mostly been looking at melodies, that is a single line of notes. But most of the music we listen to has multiple notes sounding at the same time. We usually consider three or more notes sounding together to be a chord. Some chords are clashy and dissonant, [SOUND]. Others are consonant and unremarkable, [SOUND]. And some are somewhere in between, [SOUND]. The chords that we are most familiar with are those that are built from stacking different sized thirds on top of each other. Three note chords constructed from thirds are called triads. And four note chords constructed from thirds are called seventh chords. Let's spend some time with triads. Every triad has there notes. The bottom note is called the root. The middle note is called the third, because it's a third above the root. And the top note is called the fifth, because it's a fifth above the root. Although triads are easiest to visualize when they are piled up and stacked thirds order like this, root, third, fifth, these three notes form a triad regardless of chord order or octave. As you can see, F is the root of this triad regardless of where it false, A is the third and C is the fifth. Since three notes form a triad regardless of their arrangement, you must often rearrange the notes into their stack thirds position to figure out what the root, third, and fifth of the triad are. So, this is a triad with G as its root. This is a triad with A flat as its root. Sometimes there are four notes, if two of them are the same, it may still be a triad. Here we have two Gs, a B and a D, so it's just a triad with G as its root. I always tell my students that they do themselves a favor when they memorize all the possible triads starting on each of the seven note letters A through G. I learned them this way, A C E, C E G, E G B, G B D, B D F, D F A, and F A C. Obviously, this does not include accidentals which change the quality of the triad, which we'll talk about in a future lecture. When the triads are not in stack thirds, with the root on the bottom, it's helpful to be able to quickly run through the possible triads for every note. Is this a triad? Let's try each note as the root and see if the other notes fit the triad. If E flat is the root, the triad would be E, G, B at some kind, no, that doesn't fit. If A flat is the root, it would be A, C, E, that also doesn't fit. If D-flat is the root, it would be D, F, A, and that doesn't fit either. None of the three possible triads works, so this is not a triad. It is helpful to be able to quickly go through all the possible triads to decide. That's a good start on triads. We learned that triads are three note chords in which the notes are a thrid apart. In this stacked thirds position the lowest note is the root, the middle note is the third, and the top note is the fifth no matter how the notes are arranged. Stacked thirds position is also called root position, because the root is on the bottom. In the next lecture, we'll talk about inversions of triads, in which notes other than the root are in the bottom. [MUSIC]