Microservices split an application into small, independently deployable services, whereas a monolithic architecture builds and deploys the entire application as one single unit.
Key Points: • Each microservice can be developed, tested, deployed, and scaled independently, without redeploying the entire system for a single change. • A monolith shares one codebase and one deployment, so any change requires rebuilding and redeploying the whole application. • Microservices allow teams to use different technologies per service, while a monolith is typically built on one consistent technology stack. • Scaling a monolith means scaling the entire application even if only one feature needs more capacity, while microservices let you scale just the service under load. • The trade-off is that microservices introduce distributed-systems complexity, network calls, and operational overhead that a monolith avoids by staying in a single process.
Example: Updating the search feature in a monolith requires redeploying the whole application, while in a microservices architecture, updating a Search microservice only requires redeploying that one service, without touching Payments or Inventory.
Interview Tip: A concise interview answer is:
"Microservices break an application into small, independently deployable services that can scale and evolve on their own, while a monolith ships and scales as one unit. That independence is powerful, but it trades away the simplicity of a single codebase for distributed-systems complexity like network calls and cross-service consistency."