Building a modern app stack with Apollo GraphQL and MongoDB Atlas can help teams reduce complexity by integrating scattered microservices and REST APIs into a unified schema, enabling frontend developers to query only the required data while being agnostic to where it's sourced from. A supergraph is a unified API layer built with Apollo Federation, composed of smaller graphs called subgraphs that each have their own schema, allowing teams to evolve their subgraphs independently without breaking clients. MongoDB Atlas provides a flexible document model and a reliable data layer that can run anywhere, be deployed across multiple regions and cloud providers, and scale horizontally due to its distributed nature. This combination empowers teams to innovate faster than ever before by delivering new app experiences with legacy architectures, reducing complexity, and improving performance.