An important part of becoming a good programmer is providing good documentation of your code. This includes incorporating comments right in your code that explains various elements and aspects of your code.
In the App Inventor Blocks Editor, you can add a comment to
any block of code by right-clicking on the block. Here is an example
Lesson: Code documentation is an important aspect of programming. It is especially important if you share your code with others or if you wish to work on a program that you haven't looked at in a long while -- why did I do that??