Once your programs grow longer and the logic gets more and more complicated it is a very good idea to place meaningful comments in your code. This makes it easier for the future you and your collaborators or supervisors to actually understand why your implementation is as it is.

In the very beginning your comments may be used to outline what the code block following the comment is actually doing. Once you get more familiar with Python the content of the comment should change from what the code is doing to why it is doing it.

To actually write a comment prepend it with the # character. So if you write

# In the following example you should only see
# ``Now you see me.``, and
# ``Are you still seing me?`` in the terminal.

print('Now you see me.')
# print("Now you don't.")
print('Are you still seeing me?')  # Inline comments are nice as well!

into a file and execute it you should only see

Now you see me.
Are you still seeing me?


  • You can use comments by prepending #
  • Comments are useful to explain why you did something the way you did it


  1. If you encounter some more complicated code-blocks in the future comment them. Admittedly this is not directly an exercise, but a sincere request.
  2. Really, comment your code for others and your future self. You will forget why you coded something the way you did. Still not really an exercise.