There are six named types and two wrapping types. The named types are:
If you think of a GraphQL query as a tree, starting at the root field and branching out, the leaves are either scalars or enums. They’re the fields without selection sets of their own.
The two wrapping types are:
When the named types appear by themselves, they are singular and nullable—i.e., when the client requests a field, the server will return either one item or null. Using a wrapping type changes this default behavior.