From The Tao of Microservices by Richard Rodger
The term microservices invites you to think in terms of services. You are naturally drawn to ask the question, What are the microservices in this system? Resist that temptation. Microservice systems are powerful because they allow you to think in terms of messages. If you take a messages-first approach to your system design, you free yourself from premature implementation decisions. The intended behavior of the system can be described in terms of a language of messages, independent of the underlying microservices that generate and react to those messages.