Introduction to GraphQL

GraphQL terminology

Schema

A schema defines a GraphQL API's type system. It describes the complete set of possible data (objects, fields, relationships, everything) that a client can access. Calls from the client are validated and executed against the schema. A client can find information about the schema via introspection. A schema resides on the GraphQL API server. For more information, see "Discovering the GraphQL API."

Field

A field is a unit of data you can retrieve from an object. As the official GraphQL docs say: "The GraphQL query language is basically about selecting fields on objects." The official spec also says about fields: All GraphQL operations must specify their selections down to fields which return scalar values to ensure an unambiguously shaped response. This means that if you try to return a field that is not a scalar, schema validation will throw an error. You must add nested subfields until all fields return scalars.