What is the difference between a monolith and microservices?

A monolith packages all application functionality — UI, business logic, data access — into a single deployable unit. Any change requires redeploying the entire application, and the codebase can become difficult to understand and scale over time. Microservices decompose the application into independently deployable services. The tradeoffs are significant: monoliths are simpler to develop and debug initially but become hard to scale and change; microservices offer independent scaling and deployment but introduce distributed systems complexity such as network latency, partial failure, and data consistency challenges. Neither is universally better — the right choice depends on team size, organizational maturity, and domain complexity.