Most software systems start as a single application, or monolith, where all functions—user login, payments, emails—are tangled together. This works until changes become risky and deployments feel like gambling. A practical guide advises against converting everything at once, a common mistake that kills projects. The correct first move is boring and slow: extract one microservice first.

Beginners should start by understanding their system's business capabilities, not its technical framework. Look for natural boundaries like user management or billing. Good first candidates have clear inputs and outputs, change frequently, and don't control the entire database. Authentication or email notifications are common picks because they are easy to isolate.

The process involves copying logic into a new, separate application before deleting it from the monolith. This is the Strangler Fit Pattern, allowing you to call the new service over HTTP. Only after it works reliably should you remove the old code. For data, give the new service its own database or clear access to specific tables, avoiding shared tables that recreate the monolith problem.