The best article on this topic so for.
Microservices Architecture: Advantages and Drawbacks
Clear definition:
Microservices are a way of breaking large software projects into loosely coupled modules, which communicate with each other through simple Application Programming Interfaces (APIs).
Strafulgerare, sync communication:
In this video we can see this picture
Monolith:
And the author says that the communication passes synchronously from top to bottom and then back in the reverse
But as you can see in the picture, even in a microservices architecture, you still have sync communication… but you call an REST Endpoint and you (block)wait for the response before you can go further with your program execution
Into Java 