The playground supports an easy way to write documentation for your code. It's like comments, which we are familiar with, but the Xcode renders them nicely. Let's do it step-by-step:

1. Open a playground project
2. Open the Utilities project
3. Select the File Inspector
4. Mark the option Render Documentation
5.  You should see that //: Playground - noun: a place where people can play is converted to a good-looking text