I remember struggling with creating threads without thinking and bugs while making games with Java Swing in school. At that time, I really hated threads.. Thanks to Younghan's lecture, I realized that threads are this fun. It was a lot of content, but the difficult content was explained repeatedly so that I could understand it and it was firmly embedded in my head. Thank you! In particular, Younghan's strength is that he explains the basics before explaining difficult technologies. I thought the Future interface and Executor would be really difficult in this lecture, but it was really easy because I only properly understood producers and consumers. Thank you~