A number of comments touched on this, that microservices are also an organizational strategy: you have a team that manages that particular service. My company

A number of comments touched on this, that microservices are also an organizational strategy: you have a team that manages that particular service. My company is probably typical in that we implicitly use microservices because we have consume dozens of microservices provided by other companies. We only have a handful of services we maintain, each with dedicated engineers. And what becomes a service? You want to answer two questions: 1. Does it have a concrete business justification? 2. Does it have clear functional requirements? If it has a business justification, it will get people assigned to keeping it running. If it has clear functional requirements, it will make sense to the people working on it which service does what. That's still pretty vague, so you want to look at who has done it well, and why it worked for them. Companies like AWS have been extremely successful in using microservices because every last one service has a business rationale, it's either directly making money (EC2, S3, SQS) or it supports the needs of customers who are using a service that makes money (VPC, Cloudformation, all their internal auth, billing, provisioning, security and such). The caveat there is that the big B2B service providers are not a great model for companies that have a lot of business logic.