If you have a basic understanding of memory, you will be able to listen to the lecture more easily and deeply!! Distinctions of this lecture 1. You can gain a deeper understanding by accessing memory. 2. You can understand polymorphism, one of the object-oriented features, in more detail. (The instructor emphasizes it a lot!) 3. You can gain a deeper understanding by directly imitating ArrayList. Overall It was good to be able to understand better by accessing memory!! In general, when other lectures explain the concept, I just thought it was like that and moved on, but in this lecture, I learned why it was like eating 100 sweet potatoes and drinking soda!! (It quenched my thirst, that's what I meanㅎㅎ) Thank you for creating a great lecture, instructor~! I will review and move on to the next practice!