Micronaut is a modern Java framework for building microservices. It was developed by Graeme Rocher, creator of Grails and a Spring developer. Micronaut uses annotation processing at compile time for configuration rather than reflection at runtime, making it faster and using less memory than alternatives like Spring. It supports reactive programming, cloud native features, message-driven microservices using annotations, and serverless functions. The document provides an overview of Micronaut and demonstrates how to create a simple project.