What is typography?
The craft of arranging type (choosing typefaces, weights, sizes, and spacing) to give written language its visual personality.
Typography is the second-most-recognizable thing about a brand after the logo. The difference between Stripe and Square, between Apple and Microsoft, is largely a typography choice (Söhne vs Inter, San Francisco vs Segoe) and the spacing decisions wrapped around it.
For a website, typography breaks down into typeface (which font family), type scale (the ratio of heading to body sizes), measure (line length), leading (line height), tracking (letter spacing), and pairing (how heading and body fonts work together). Get the type scale right and almost everything else falls into place.
Context.dev's font API returns the actual fonts a website uses, family names, weights, sources, and where each one appears. For brand-aware product UIs, replicating a customer's typography is the fastest path to a "this looks native to my brand" reaction.