What are compound components in React?

Compound components are a pattern where multiple components work together to form a complete UI element, sharing implicit state via React Context. Think of HTML's <select> and <option> — they work together through an implicit relationship. React example: <Tabs><Tabs.Tab id="1" label="First" /><Tabs.Content id="1">Content...</Tabs.Content></Tabs>. The Tabs parent manages the active tab state and shares it via Context; Tabs.Tab and Tabs.Content read from that Context. Implementation: Tabs creates a context with the active ID and setter; the sub-components are attached as static properties (Tabs.Tab = TabComponent). Benefits: flexible API — consumers can reorder, omit, or add sub-components; implicit state sharing without prop drilling; great for UI component libraries (modals, tabs, accordions, dropdowns). Vs render props: compound components are more declarative and composable; render props can be more flexible for injecting dynamic content. Libraries like Radix UI heavily use compound components.