In this episode of 'Back to Basics', Venu explores how to modernize enterprise APIs using serverless GraphQL patterns with AWS AppSync. He demonstrates how to unify data across existing microservices, connecting front-end applications to multiple data sources with a single request. The video covers the architecture of an e-commerce application using AWS AppSync as a GraphQL data layer, showcasing how it interfaces with different microservices including a REST-based user service and a containerized payment service. Venu explains the workflow of how AppSync uses resolvers to fetch and consolidate data from various sources, providing a scalable and efficient solution for API composition. The episode also touches on new features of AWS AppSync, including private APIs and merged APIs, which enable better team collaboration and management of GraphQL APIs at scale.