GraphQL / Apollo

GraphQL was developed by Facebook as an alternative to the standard REST API architectural style. It was designed to be faster and more flexible/efficient. GraphQL lets developers construct requests that can pull data from multiple data sources in a single API call.

API developers use GraphQL to create a schema to describe all the possible data that clients can query through that service.

A GraphQL schema is made up of object types, which define which kind of object you can request and what fields it has.

As queries come in, GraphQL validates the queries against the schema. GraphQL then executes the validated queries.

The API developer attaches each field in a schema to a function called a resolver. During execution, the resolver is called to produce the value.