I’m starting to see harmony differently
Quick note: I'm Brazilian and English isn't my first language, i used google to help correct my English. I'm still learning, so I'd appreciate answers without overly complex English if possible.
Edit: Guys, I really appreciate all the knowledge and different perspectives you’re sharing here. I’m really enjoying the discussion and learning a lot from all of this, so thank you! I have a basic understanding of the terminology — intervals, tonic, dominant, chord types, scales, Roman numerals, etc. — but I’m more interested in the feeling behind these relationships: why certain combinations of notes create a certain tension, resolution, or character, and how those relationships work together. The C–F# example was just an example, not really the main point.
I started playing guitar about 10 years ago, but I never really went deep into music theory. I'd occasionally look things up, but I never studied it in a very structured or in-depth way.
Recently, I started learning more about intervals, like minor seconds, major thirds, and so on. And honestly, it made me start seeing harmony differently.
I'm starting to realize that maybe I don't necessarily have to be locked into one tonality or scale. I can play notes outside the scale, and they can still make musical sense depending on the interval and the relationship between the notes.
For example, if I'm playing in C major and play F#, instead of simply thinking "F# is outside the key," I can think of it as an augmented fourth (#4) or diminished fifth (b5) relative to C.
This made me wonder: is there a way to study harmony from this perspective? Thinking more about intervals and the relationships between notes, rather than mainly thinking about which notes belong to a particular scale?
And more importantly, how do I use this way of thinking to actually continue a harmony? For example, if I play a certain interval and like the tension or feeling it creates, how can I understand where I could go next?
I'm not sure if I'm describing this correctly, so I'd really appreciate any recommendations on what I should study or search for.