GraphQL is being used to provide personalized product recommendations in e-commerce applications. This is achieved by adding a new field to the User type that fetches recommended products, and another field to the Product type for fetching related products. The use of GraphQL allows for efficient querying and resolving of data without duplicating business logic or making separate calls to a recommendation service. Apollo Federation is used to link services together in a discovery subgraph, solving the N+1 problem and optimizing queries to use the fewest requests possible. With this schema in place, e-commerce applications can now focus on optimizing the recommendation engine without breaking existing use cases, and consider adding new optional arguments for selecting different types of recommendations.