Color theory is simply the set of ideas that explain how colors relate to one another and why some combinations feel right. You don't need to memorise it, but a few basics make choosing and building palettes far easier.
The color wheel
The color wheel arranges hues in a circle so you can see their relationships at a glance.
- Primary colors — red, yellow and blue. You can't mix other colors to make them.
- Secondary colors — orange, green and purple, made by mixing two primaries.
- Tertiary colors — the in-between hues like red-orange or blue-green.
Colors near each other on the wheel feel harmonious; colors opposite each other create contrast. That single idea powers most color schemes.
The three properties of every color
Any color can be described by three things:
- Hue — the color itself (red, green, blue…), its position on the wheel.
- Saturation — how vivid or dull it is. High saturation is intense; low saturation is greyed-out.
- Lightness (or value) — how light or dark it is, from black to white.
This is exactly what the HSL color model captures — see hex, RGB and HSL explained. Adjusting saturation and lightness while keeping the hue is the secret to building tints and shades that belong together.
Warm vs cool colors
Reds, oranges and yellows read as warm — energetic and inviting. Blues, greens and purples read as cool — calm and steady. Most palettes lean one way, with the other used sparingly for contrast.
Put it into practice
The fastest way to learn is to play. Open the palette generator and press the spacebar to see harmonious combinations instantly, or explore ready-made palettes and notice which hues sit together.