As an application and team grow, one large codebase can start slowing everyone down. A small change touches shared code. Deployments need careful coordination. One team can end up waiting for another team before it can release.

Microservices split a system into smaller services that can be deployed on their own. Each service owns a clear business area, such as orders, payments, inventory, search, or notifications.

This can help teams move faster, but it is not free. Services now talk over the network. Data lives in different places. Instead of operating one application, you operate many.

This chapter explains what microservices are, how to choose service boundaries, how services communicate, how data consistency works, how to handle failures, and when microservices are worth the extra work.