To me, a microservice architecture is about splitting up monolithic applications into smaller components, which achieves two major goals:

• Faster development, enabling continuous deployments
• Easier to scale, manually or automatically

A microservice is essentially an autonomous software component that is independently upgradeable and scalable. To be able to act as an autonomous component, it must fulfill certain criteria as follows: 

• It must conform to a shared-nothing architecture; that is, microservices don't share data in databases with each other!
• It must only communicate through well-defined interfaces, for example, using synchronous services or preferably by sending messages to each other using APIs and message formats that are stable, well-documented, and evolve by following a defined versioning strategy.
• It must be deployed...