What is Microservices?

In a microservices architecture, an application is decomposed into discrete services: an authentication service, a billing service, a notifications service, an AI inference service. Each is independently deployable, independently scalable, and can use a different programming language or database if appropriate.

Benefits: individual services can scale under load without scaling the entire application; one service crashing doesn't take down the whole system; different teams can work on different services without coordinating on a single codebase. These advantages become meaningful at scale.

The trade-offs are real: distributed systems are operationally complex. You need service discovery, distributed tracing, inter-service authentication, and careful management of API contracts between services. For most early-stage SaaS products, a well-structured monolith is faster to build and easier to operate — extract services only when a specific bottleneck demands it.