Spring GraphQL is a framework that allows you to build GraphQL APIs using the Spring Framework, a popular framework for building Java-based applications. GraphQL is a query language for your API, enabling clients to request exactly the data they need, which can be more efficient than traditional REST APIs for certain use cases.

Here are some key points about Spring GraphQL:

1. Integration with Spring: Spring GraphQL seamlessly integrates with the Spring ecosystem, making it easy to incorporate GraphQL into your existing Spring-based applications.

2. Schema-First Approach: Like other GraphQL implementations, Spring GraphQL typically follows a schema-first approach. You define your API schema using the GraphQL schema definition language (SDL), and the framework generates Java classes to represent the schema types and resolvers.

3. Data Fetching: Resolvers are responsible for fetching the data for a particular GraphQL query. Spring GraphQL provides mechanisms for defining these resolvers and fetching data from various sources, including databases, REST APIs, or other services.

4. Query Execution: Spring GraphQL handles the execution of GraphQL queries, including field resolution, data validation, and error handling.

5. Annotations: Spring GraphQL often uses annotations to mark classes and methods that are involved in handling GraphQL queries. For example, you can use @GraphQLQuery to annotate methods that act as resolvers for specific fields in your schema.

6. Subscriptions: Some Spring GraphQL implementations support real-time capabilities through GraphQL subscriptions, allowing clients to receive updates when specific events occur.

7. Security: You can integrate security mechanisms into Spring GraphQL to control access to your GraphQL API using Spring Security.