PropTypes in React serve as a type-checking mechanism that validates the types of props passed to a component at runtime, helping to improve code reliability and debugging by issuing warnings when props do not match the expected types. Originally part of React but now a standalone package since React 15.5, PropTypes can be useful particularly in versions of React lower than 19 or when dealing with unpredictable external data in production. While PropTypes provide runtime warnings, they do not enforce type safety like TypeScript, which checks types at compile time and prevents incorrect types from being passed. The article provides guidance on how to implement PropTypes in React applications and highlights their limitations compared to TypeScript, suggesting that developers consider using TypeScript or other schema validation libraries like Zod for more robust type safety. Additionally, it discusses how platforms like Contentful can streamline development by ensuring data consistency and type safety through tools such as GraphQL and TypeScript, enhancing the development workflow and reducing runtime errors.