Schema definition language Object types Scalar types Non-null types List types Enums Interfaces Union types Input object types Schema root operation types

Field definitions Field arguments Default argument values Field aliases Nested selections Descriptions and documentation Deprecated fields Custom scalar declarations Resolver field shape Selection-set validation

Basic query operation Named query operations Operation variables Variable default values Multiple root fields Nested object queries Query aliases Arguments in queries Introspection __typename Introspection __schema

Named fragments Inline fragments Fragment type conditions Fragment variables pattern @include directive @skip directive Custom directives Directive locations Reusable selection sets Interface fragment matching

Basic mutation operation Mutation input objects Mutation payload types Multiple mutation fields Mutation variables Create mutation pattern Update mutation pattern Delete mutation pattern Mutation error payloads Optimistic response shape

Subscription operation Subscription payloads Subscription arguments Subscription variables Event filtering pattern Single root subscription rule WebSocket subscription shape Live event payloads Subscription authorization Subscription cleanup semantics

Field-level errors Partial data with errors Null bubbling Authentication context Authorization at field level Query depth limiting Query complexity limiting Persisted queries N+1 query problem DataLoader batching pattern

Backward-compatible schema changes Deprecation workflow Adding optional fields Changing nullability safely Schema versioning strategy Federation @key Federation @external Federation @requires Federation entity references Gateway composition concepts