Kent C. Dodds: 0:00 Eventually you're probably going to want to render arrays. That's what this exercise is all about. I'm going to invite you to read the background yourself and see what problem is existing in this component as we've rendered it and see how you can solve this problem by using the key prop as described in this background.

0:19 This is a pretty simple quick fix. It's a single line of code, a single prop that you add, but I want you to play around with it and explore and try to figure out why it's behaving in the way it does, and why your fix of adding the key prop fixes that. I'll see you on the other side of the exercise to explain it.

0:36 Also, feel free to take a look at this extra credit for that focus demo, which is more of a demo than any sort of exercise.