.graphql File — GraphQL Schema/Query

GraphQL files contain schema definitions, queries, mutations, and subscriptions for the GraphQL query language and runtime, developed by Facebook in 2012 and open-sourced in 2015. GraphQL provides a type system for defining API data structures and a query language that allows clients to request exactly the data they need, solving the over-fetching and under-fetching problems common with REST APIs. GRAPHQL files can contain schema definitions (types, interfaces, unions, enums, input types), query operations for reading data, mutation operations for modifying data, subscription operations for real-time updates, and fragments for reusable query components. The GraphQL type system enables powerful developer tooling including autocompletion, validation, and code generation. GraphQL has been adopted by major companies including GitHub (their primary API), Shopify, Twitter, and Airbnb. The ecosystem includes Apollo, Relay, and urql as client libraries, and Apollo Server, GraphQL Yoga, and Hasura as server implementations. GraphQL files are used in schema-first development, persisted queries, and code generation workflows that create typed client libraries from schema definitions.