The Strong Chords - or primary chords - these are the ones that give the key you are in their strongest feeling. In the beginning of building your own songs, there are three of these primary chords, The One, The Four, and the Five. What the heck does that mean you might ask. Keys are named after the first note in the scale you use. If you are playing in the key of C Major, that means you are using the major scale starting on C. This also means that the “One” chord is also the C chord. It is a major chord. The next chord, the “Four” is the chord F Major. (C D E F - forth one), and the Five Chord is G Major. When you play in the key of C Major these three chords with be the major structure of the song. This doesn’t mean that you can never use any other chords, but these three give the strongest feeling of resolution, turn around, completion. Kind of like the hanger that lies underneath a nice piece of clothing. This progression - The 1 4 5 - is the underlying pattern of many songs.
So first you decide what key you will play in, if it is minor or major scale, and you have stated what note you are basing the song one, the scale, and the three primary chords.
In the Key of D Major the One Chord is D Major, the Four Chord is G Major, and the Five is A Major. In all major Keys the 1, 4 and 5 are always major Chords because the spacing of the major scale compels them to be this way. I will discuss this more when we look at chord structure.
Minor Keys are named by the first note you choose, then you apply the minor scale to get the notes of the key. Again the three primary chords are the One the Four and the Five. In the case of the minor scale each of these is a Minor chord. Trust me on this until we get to chord structure.
This is not to say that you can not use other chords, just that this is a very common and strong combination. In fact that is both the best and worst reason to use it, depending on your goal. If you want a bouncy dance sound like say 60’s dance rock, 1 4 5 is the way to go, as with blues, a lot of classical music, many types. It has a very strong start and end, turn around, a kind of up down bouncy feel. But what if you don’t want that? You can reduce the feel by slowing down the tempo, but there are other chord progressions that work for other feelings. We will get to those later.