What is a GraphQL mutation?

A mutation is a GraphQL operation for creating, updating, or deleting data — the write equivalent of a query. Example: mutation { createUser(name: "Alice", email: "alice@example.com") { id name } }. Like queries, mutations can return data — you specify which fields you want back after the write operation. Multiple mutations in a single document execute serially (one after another), unlike query fields which can be fetched in parallel. This serial execution prevents race conditions when performing multiple writes.