Explain the internal working of Spring Boot.

Spring Boot is a framework built on top of the Spring framework that aims to simplify the process of building and deploying production-ready applications. It achieves this by providing a set of conventions and defaults that streamline application setup, configuration, and development. Here's an overview of how Spring Boot works internally:

Starter Dependencies: Spring Boot uses starter dependencies to simplify the inclusion of commonly used libraries and frameworks. These starters are essentially dependency descriptors that pull in all the necessary dependencies to get started with a particular functionality (e.g., web applications, data access). They help in avoiding version conflicts and simplify dependency management.

Autoconfiguration: One of the key features of Spring Boot is autoconfiguration. Spring Boot automatically configures your application based on the dependencies you have added to your project and the environment you are deploying to. It scans the classpath for libraries, frameworks, and other components and configures beans that are needed for your application to function.

Embedded Servers: Spring Boot includes embedded servers (such as Tomcat, Jetty, or Undertow) which allow you to run your application as a standalone Java application. These servers are included as dependencies and are automatically configured based on your application's needs. You don't need to deploy your application to a separate server; Spring Boot can package everything into a single executable JAR or WAR file.

Spring Boot Starters: As mentioned earlier, starters are a set of convenient dependency descriptors that you can include in your application. Each starter provides a set of dependencies related to a specific aspect of the application (e.g., web, data, messaging). For example, including the spring-boot-starter-web starter brings in dependencies for building web applications using Spring MVC and embedded Tomcat server.

Spring Boot CLI (Command Line Interface): Spring Boot CLI allows you to run and test Spring Boot applications from the command line. It uses Groovy-based domain-specific language (DSL) for quickly prototyping and running Spring Boot applications.

Spring Boot Actuator: Actuators are included in Spring Boot to help you monitor and manage your application. Actuators expose various endpoints (such as health, metrics, environment, etc.) over HTTP or JMX, which can be used to understand and manage your application's behavior in production.

Configuration Properties: Spring Boot allows you to externalize your configuration so that you can work with the same application code in different environments (dev, test, prod) with different configurations. You can use properties files, YAML files, environment variables, or command-line arguments to configure your application.

Spring Boot Annotations: Spring Boot provides annotations like @SpringBootApplication that combines @Configuration, @ComponentScan, and @EnableAutoConfiguration annotations into a single annotation for convenience. There are also annotations like @RestController, @GetMapping, @PostMapping, etc., that simplify the development of RESTful web services.

Overall, Spring Boot's internal workings revolve around simplifying and accelerating the development of production-grade applications by minimizing boilerplate code, providing sensible defaults, and integrating well with the Spring ecosystem and third-party libraries.