16. What is GraphQL and what are its advantages compared to REST?

GraphQL is a query language for APIs developed by Facebook that allows clients to specify exactly what data they need. Unlike REST, where requests are predefined on the server, GraphQL gives the client more control over the data they receive. Here are some advantages of GraphQL compared to REST:

1. Flexible Queries: The client can request exactly the data they need, reducing the amount of data transferred and improving performance.

2. Single API for Multiple Resources: GraphQL allows fetching data from multiple sources in a single query, eliminating the need for multiple HTTP requests to different endpoints.

3. Strong Typing: The GraphQL schema is strongly typed, helping validate queries and responses and making documentation easier to create.

4. Better Versioning: Instead of creating new API versions, new fields and types can be added to the GraphQL schema, allowing for growth without breaking existing clients.

5. Introspection: GraphQL provides introspection capabilities, allowing clients to dynamically discover available types and operations in the API.

GraphQL is a powerful tool that offers greater flexibility and control over data, which can significantly improve the performance and usability of web applications.