What is GraphQL? - Definition & Meaning

Definition

GraphQL is a query language and runtime for APIs, developed by Facebook (Meta) in 2012 and open-sourced in 2015. Unlike REST APIs, where the server determines which data is returned, GraphQL allows clients to specify exactly what data they need in a single request.

Technical explanation

GraphQL defines a strongly typed schema that describes all available data and operations through types, queries, mutations, and subscriptions. Queries fetch data, mutations modify data, and subscriptions provide real-time updates via WebSockets. The schema acts as a contract between client and server, enabling automatic documentation and code generation through introspection. Resolvers are the functions that connect each field in the schema to the actual data source. GraphQL prevents over-fetching (retrieving too much data) and under-fetching (retrieving too little data, requiring additional requests) by letting clients specify exactly what they need. DataLoader batches and caches database queries to solve the N+1 query problem. Fragments allow defining reusable pieces of query logic. Persisted queries improve performance and security by storing queries server-side. Apollo, Relay, and urql are popular client libraries providing caching, optimistic updates, and state management.

How MG Software applies this

At MG Software, we use GraphQL when complex data relationships and flexible data needs justify it. For projects with mobile apps and multiple frontends, GraphQL offers the advantage that each client fetches exactly the data it needs without redundant information. We combine GraphQL with TypeScript code generation so types automatically stay synchronized between client and server. For simpler APIs, we choose REST due to lower complexity.

Practical examples

• A news app fetching the title, author, first three paragraphs, and related articles in a single GraphQL query, instead of making four separate REST calls for the same information.
• An e-commerce platform where the mobile app fetches a lightweight product list (only name, price, and thumbnail) while the desktop version gets reviews, specifications, and related products through the same API.
• A dashboard application receiving real-time updates via GraphQL Subscriptions when new orders come in, without having to poll the server.

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