Typography is not about choosing a font. It's about building a system of relationships — between letters, between words, between lines, between the text and the space it occupies.
The best interfaces use type as their primary material. Not illustrations, not icons, not gradients — type. A well-set heading at the right size, weight, and spacing communicates hierarchy faster than any visual decoration.
Consider three levels of scale: the label (tiny, uppercase, monospaced), the heading (large, bold, tight tracking), and the body (comfortable, readable, generous line-height). These three relationships — applied consistently — can structure an entire interface without a single border or divider.
The sites that get this right share a pattern: they treat typography decisions with the same rigor as engineering decisions. Font pairing isn't aesthetic preference — it's a system design choice. Line-height isn't a CSS property — it's the rhythm of the page.