Consider you want to make a song. And let's just say, the root note is in C (the most common root note ever!!) and we're gonna use major scale. And then, the next question is, what chords i can use to make this song? Okay, im here to save you, dont worry, hehe. In this post, i will give you the idea, what chords you can use and why you can use them. And what im gonna give you here, is a basic music theory. Hopefully it's enough for you to make some song. Maybe you will encounter some song that out of this rule, but hey...music is not mathematics. You can break the rules, if it's good for you and/or your listeners. But of course if you a complete beginner, it's just save to follow the rules first. Without further sayings, let's begin, shall we? We continue with the scenario, which is make a song in C major. As we all know, a C major scale is C D E F G A B. There's common rule, that we can use pattern (Major-Minor-Minor-Major-Major-Minor-Diminished) over a maj