The GraphQL data query language is:

  • A specification. The spec determines the validity of the schema on the API server. The schema determines the validity of client calls.

  • Strongly typed. The schema defines an API's type system and all object relationships.

  • Introspective. A client can query the schema for details about the schema.

  • Hierarchical. The shape of a GraphQL call mirrors the shape of the JSON data it returns. Nested fields let you query for and receive only the data you specify in a single round trip.

  • An application layer. GraphQL is not a storage model or a database query language. The graph refers to graph structures defined in the schema, where nodes define objects and edges define relationships between objects. The API traverses and returns application data based on the schema definitions, independent of how the data is stored.

It allows for reading and writing through queries and mutations (see GraphQL documentation).