This is a really great lecture that explains the fundamental principles and concepts of next.js in detail. While listening to the TypeScript lecture, I felt that this person explained the concepts step by step, so it was really good to learn when I first started studying, and so I was using it while studying next.js, and when Jeong-hwan's next.js lecture came out, I bought it right away! This lecture really met my expectations 200%. It's so great because I can learn concepts I didn't know in detail. I'm still in the page router part, so I haven't even gotten into the app router, but I'm already very satisfied. It explains important basic concepts such as the rendering method before implementing the function by writing code, and the concept of how the framework works in an easy-to-understand way, and it also shows the results that can be bothersome to show in detail, such as the build or network request process... Where else can you find a more friendly lecture? I think I can study next.js from the basics to advanced levels in depth. I really, really recommend it to those who are just starting to understand the concepts!