This document discusses lessons learned from implementing microservices in production environments. It outlines both the benefits of microservices, such as scalability and fault tolerance, as well as challenges, including loose coupling, greenfield development, and culture. Specific lessons include containing failures, using caching and logging for fault tolerance, building contracts to enable loose coupling, starting with a monolith then extracting services, and ensuring an automated testing and deployment culture. The key takeaway is that microservices are difficult to implement and the challenges must outweigh the benefits for an organization.