Primary / secondary / ghost / destructive / brand.
Standard button with 5 variants + 3 sizes. Brand-color focus ring, loading spinner, disabled state. Foundation primitive every other component composes against.
import { Button } from "@/components/ui/button";
<Button variant="primary">Open in Dock</Button>
<Button variant="ghost" size="sm">Cancel</Button>components/ui/ folder. You own the code.