GraphQL

A query language for APIs where the client specifies exactly what data it needs, and the server returns exactly that — nothing more, nothing less.

Example: A mobile client fetches only `user.name` and `user.avatar` instead of the full user object a REST endpoint would return.

In practice: Solves over-fetching and under-fetching cleanly, but introduces complexity on the server side — schema design, resolver performance, and the N+1 query problem all need deliberate handling.

Debated: Often introduced to solve a problem (field flexibility) that API versioning or query parameters would have solved more simply — the tooling and mental model overhead is non-trivial.

• alternative to REST
• can lead to N+1 query problem