Spring Boot is essentially a framework for rapid application development built on top of the Spring Framework. With its auto-configuration and embedded application server support, combined with the extensive documentation and community support it enjoys, Spring Boot is one of the most popular technologies in the Java ecosystem as of date.

Here are a few salient features:

Starters – a set of dependency descriptors to include relevant dependencies at a go
Auto-configuration – a way to automatically configure an application based on the dependencies present on the classpath
Actuator – to get production-ready features such as monitoring
Security
Logging