Microservices architecture is a software development approach where an application is built as a collection of small, independent services, each handling a specific business function. Spring Boot simplifies microservices development with its lightweight, modular framework, offering features like embedded servers, RESTful APIs, and easy integration with tools like Spring Cloud for service discovery, load balancing, and distributed tracing. This architecture enables scalability, resilience, and faster deployment cycles, making it ideal for modern cloud-native applications.