The first computer mouse was designed using a roll-on deodorant tube and a butter dish. It didn’t
work with a computer, of course, but the prototype helped people understand the idea and think about
how a computer mouse might work.
In app development, you might prototype a user interface to see how an app would look, without
worrying about the blocks. You could also prototype some of the blocks to see how the app would
work, without worrying about the interface. App prototypes are just early versions of part of the app
to help programmers and users find and solve problems.