I have completed the basics right after the introduction! While reviewing the lecture, I plan to study JPA Utilization 1 right away!! While really listening to the lecture, I learned why Spring was created, how well Spring maintained polymorphism and SOLID, the importance of dividing roles and implementations, and why we need to rely on abstraction, and for that, I learned about the core technologies of Spring, such as DI containers and dependency injection. As the name of the lecture suggests, the core principles (Core) of Spring were explained in detail and easily. Thank you so much for making such a great lecture!!