GraphQL is an API query language that was invented in 2012 by Facebook, and it has gained popularity since then. It is a full-featured language with a specification, just like SQL, and it allows clients to request exactly the data they need, reducing over-fetching and under-fetching issues. GraphQL APIs are structured as nodes and edges, which lets clients fetch data directly in a single query. Unlike REST, which relies on standard HTTP methods and status codes, GraphQL is more explicit and allows for more control over the data retrieved. GraphQL has its own playground tools, such as GraphQL Playground, which provide autocompletion and let users send requests and see responses directly in one window. While implementing a GraphQL server can be more complex than a REST API, it offers flexibility and single-request capabilities, making it suitable for applications with evolving schema requirements.