Controllers are the integration point between the model and view in the MVC paradigm. They act like the glue that binds together everything while taking care of business logic execution and routing. The following Maven starter dependency needs to be added to enable Spring Web MVC:

<dependencies>
   ...
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-web</artifactId>
   </dependency>
</dependencies>

The preceding dependency will import the servlet, Spring, and Tomcat dependencies to enable the successful writing of servlet-based web applications using Spring.