Spring Boot

Spring Boot builds on Spring Framework to provide opinionated defaults, automatic configuration and embedded servers, so an application runs as a single executable rather than being deployed into a separate container. Spring Initializr generates a starting project, and the wider ecosystem covers Cloud, Data, Security, Integration, Batch and AI.

Automatic configuration is the change that mattered and it addressed a genuine reputational problem. Enterprise Java had become associated with lengthy XML configuration before any code ran, which drove a generation of developers toward other languages entirely. Inferring configuration from what is on the classpath removed most of that, and a working web application became a matter of minutes.

Embedding the server is the second structural decision. Producing a runnable artefact rather than something deployed into an application server matches how software is now shipped, in containers and on platforms that expect a process rather than a deployment target.

The trade off is worth naming honestly. Opinionated defaults are excellent until an application needs to disagree with one, and understanding why something is configured a particular way then requires knowing what the automatic configuration decided and why.