Definition: Microservices are an architectural style where an application is split into small, independently deployable services, each owning a single business capability, its own data, and communicating over lightweight APIs (typically REST/gRPC or async messaging). Key properties: Autonomy, bounded context, independent deployability, polyglot tech stack, and fault isolation — enabling faster delivery and easier scaling compared to monoliths. Approach: Design by domain-driven design (DDD) — identify bounded contexts, model services around business capabilities, and define clear contracts (APIs) and ownership for data and behavior. Construction steps: Define service boundaries and data ownership. Design API contracts (versioned) and choose sync/async communication. Implement services with well-defined interfaces and small, focused codebases. Provide each service with its own datastore when needed to avoid coupling. Infrastructure & delivery: Automate with CI/CD pipelines, containerize services (Docker), orchestrate with Kubernetes or a managed service, and use service discovery/load balancing. Reliability & observability: Implement circuit breakers, retries, timeouts; centralize logging, distributed tracing, metrics (Prometheus/Grafana), and set up health checks and alerting. Testing & governance: Use contract testing, consumer-driven tests, end-to-end integration tests, and enforce API standards, security (authn/authz), and rollback strategies for safe evolution.