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Colour theory basics 0:24
A 24-second explainer of Colour theory basics, narrated over the same demo you can try yourself.
Try the interactive Colour theory basics demo
What this video covers
Colour theory is the set of relationships - on the colour wheel and in the dimensions of hue, saturation and lightness - that explain which colours work together and why. From a single base colour you can derive harmonious schemes (complementary, analogous, triadic) that give an interface a coherent, intentional palette instead of a random clash.
Pick a base colour and watch a whole scheme fall out of the wheel - complementary, analogous, triadic - each with a different feel. That's colour theory: not magic taste, but relationships you can reason about. Build a palette from one base plus neutrals and it looks deliberate; throw together unrelated hues and it looks accidental. Harmony is a system, and systems are learnable.