What is GraphQL?
GraphQL is a query language and runtime for APIs that allows clients to request exactly the data they need in a single request, avoiding the over-fetching and under-fetching problems common with traditional REST APIs.
How Does GraphQL Work?
Developed by Facebook in 2012 and open-sourced in 2015, GraphQL lets clients define the structure of the response they need using a strongly typed schema. Instead of multiple REST endpoints returning fixed data shapes, a single GraphQL endpoint accepts queries that specify exactly which fields to return. This makes it especially efficient for mobile applications and complex UIs that need data from multiple resources in a single round trip.
A GraphQL server defines a schema that describes all available types, fields, and relationships. Clients write queries against this schema, and the server resolves each field using resolver functions that fetch data from databases, other APIs, or any data source. GraphQL also supports mutations for writing data and subscriptions for real-time updates. While it adds complexity to the server side, GraphQL significantly simplifies client-side data management and reduces network overhead.