React Guideline: Props — Avoid prop drilling. Description: Use context or composition for deeply nested data. Do: Context for global data composition for UI. Don't: Passing props through 5+ levels. Good Example: <UserContext.Provider>. Bad Example: <A user={u}><B user={u}><C user={u}>. Severity: Medium. Docs: https://react.dev/learn/passing-data-deeply-with-context.