The text discusses query batching in the context of GraphQL, a query language used for APIs. Query batching involves sending multiple queries to the server in one request, reducing the number of roundtrips and improving efficiency. This can be achieved through caching or by using a technique called "query merging", which combines multiple queries into a single root query with aliases. The text also introduces transport-level batching, where the server processes an array of queries and responds with an array of results, making it easier to debug and more efficient. The authors discuss how Apollo Client implements these techniques and provide examples of how developers can use them in their applications.