microservice typically implements a set of distinct features or functionality. Each microservice is a mini‑application that has its own architecture and business logic

A monolithic application is a single-tiered software application in which different modules are combined into a single program

Microservices, or microservices architecture, are the modern methods of designing software applications that compartmentalize the software into chunks of small and independent services

Egress listeners

Ingress listeners

As we're now recognizing, often the best way to find out if a software idea is useful is to build a simplistic version of it and see how well it works out

You cannot assume that you can take an arbitrary system and break it into microservices. Most systems acquire too many dependencies between their modules, and thus can't be sensibly broken apart. I've heard of plenty of cases where an attempt to decompose a monolith has quickly ended up in a mess. I've also heard of a few cases where a gradual route to microservices has been successful - but these cases required a relatively good modular design to start with.