How do you assess your experience with Spring, Spring Boot? What have you done? Do you know how it works under the hood?

I have worked with Spring and Spring Boot in several projects, where I developed REST APIs, integrated databases using Spring Data JPA, configured security with Spring Security, and wrote custom configurations. I used Spring Boot's auto-configuration for quick application startup and profiles for environment management.

Under the hood, Spring uses inversion of control (IoC) and dependency injection (DI) through the ApplicationContext container, which manages the lifecycle of beans. Spring Boot is built on top of the Spring Framework and adds auto-configuration that automatically configures the application based on dependencies and settings, significantly simplifying development.

For example, when using Spring Boot with the spring-boot-starter-web dependency, it automatically configures an embedded Tomcat server, MVC, and Jackson for JSON serialization if they are present in the classpath.