It was really good because I was able to get a feel for polymorphism when I practiced only with Java in the beginning. After that, I also understood the overall concept of Spring well, but I was a little worried because I was a little vague about how these would be used when creating an actual web application. Fortunately, the utilization section was on the roadmap. I will keep what I learned in mind and move on to the utilization section. Thank you.