async-graphql/docs/en/src/define_schema.md

Schema

After defining the basic types, you need to define a schema to combine them. The schema consists of three types: a query object, a mutation object, and a subscription object, where the mutation object and subscription object are optional.

When the schema is created, Async-graphql will traverse all object graphs and register all types. This means that if a GraphQL object is defined but never referenced, this object will not be exposed in the schema.