GraphQL and REST are two prevalent API architectures used to facilitate data exchanges between clients and servers, each with distinct operational methodologies and advantages. REST relies on multiple endpoints and standard HTTP methods like GET, POST, PUT, and DELETE to perform CRUD operations, and it excels in simplicity, caching, and widespread adoption, despite challenges like over-fetching and under-fetching. GraphQL, developed by Meta, uses a single endpoint and allows clients to specify exactly what data they need through queries, reducing unnecessary data transfer and supporting complex data requests in one call. While REST is known for its robust security features and ease of implementation, GraphQL offers flexibility and real-time capabilities, albeit with a steeper learning curve and caching complexities. Choosing between the two depends on project needs, with REST being ideal for simplicity and scalability in enterprise applications, and GraphQL being suited for modern, frontend-driven applications requiring efficient and flexible data fetching.