What does “appendix” mean?

In this article, we’re going to discuss what the word “appendix” means and why you see this section in most of my courses.

Firstly, I was surprised that so many students didn’t understand what an “appendix” is, because the concept already appears in many books.

This is actually why I renamed this section to “Appendix / FAQ” since I hoped that if students never heard of the word “appendix”, at least they must know what “FAQ” means.

Side note: “FAQ” stands for “frequently asked questions”.

Let’s use the Merriam-Webster definition of “appendix”: https://www.merriam-webster.com/dictionary/appendix

Appendix: supplementary material usually attached at the end of a piece of writing

“Ok sure, but do you have any examples?”

Here is an example from one of the most famous machine learning books of all time (Bishop’s Pattern Recognition and Machine Learning):

I hope the concept is obvious (please let me know if it’s not obvious for you).

The purpose of an appendix is to provide material which is related but not part of the main content.

The main content of PRML covers topics like Linear Regression, K-Nearest Neighbor, Gaussian Mixture Models, etc.

Obviously, “Data Sets” and “Properties of Matrices” are not machine learning algorithms. But that doesn’t mean they shouldn’t belong in a machine learning book!

What do I cover in my Appendices?

Now that you have one example of an Appendix, let’s look at another: the one existing in my courses. What is covered? Examples:

  • Supplementary technical content to help students with common problems
  • Installing Python and Python libraries / environment setup
  • Instructions for coding exercises
  • Tips for differentiating Python 2 vs. Python 3
  • Why many beginners have the wrong idea about Jupyter Notebooks
  • How to succeed in the course (obviously very important!)
  • Machine Learning and AI Prerequisite Roadmap / What order should I take your courses in?
  • Where to get free material, sign up for my newsletter, etc.

I hope that it’s common sense to understand why these would be included in the course.

Why are these topics included in the Appendix?

The important thing to remember is that you are not the only person taking the course. In most cases, there are thousands of students in each course.

I’ve been teaching these courses for 6+ years now.

Obviously, I’ve grown familiar with the most common student questions and concerns.

Therefore, it’s convenient for me to address these questions and concerns before they ever reach my inbox.

This saves the student time (because they don’t end up frustrated and then emailing me) and it saves me time (because I don’t have to copy and paste the same response again and again).

Why would you be opposed to that?

Are you against me helping other students?

Why can’t you include it in a separate course?

This is a silly idea. It only makes things harder to find for your fellow students.

Would you suggest to Christopher Bishop that he should make a separate book just about “Data Sets” and “Properties of Matrices”?

Do you think Appendices should be removed from all books and sold as separate books?

If you can’t answer “yes” to this question, then you have just realized your thinking is inconsistent. 😉

It is selfish

For some students, it seems that there is some selfishness involved.

They want the course to be only for them, not for anyone else.

They don’t care if these lectures answer the most common questions.

They don’t care if students would have more difficulty and more obstacles if these questions weren’t answered in an obvious and convenient place (e.g. without having to go to a different website, URL, an entirely different course, or having to email me and wait for an answer).

Key point: adding things for other students doesn’t take anything away from you.

It doesn’t harm you in any way

Maybe students really believe they are not being selfish.

Maybe students really believe that the existence of the appendix really hurts them.

My question is: why / how?

How does answering the questions of other students hurt you?

The course promises to teach Topics A, B, C.

I presume you took the course to learn Topics A, B, C.

The course has materials on Topics A, B, C.

Therefore, you got what you should have expected from the course: Topics, A, B, C.

The course has extra materials I’ve added to answer common student questions.

Adding extra materials doesn’t take away anything from you.

Does it?

As always, I have no idea why students can disagree with such obvious and logical common sense.

So, if you are one of those students, please just email me using the contact form above and explain your thinking. I am eager to listen!

“I thought the course was going to be 10 hours long but it only had 8 hours of main content!”

This is another one of the silliest ideas I’ve heard.

Which is correct?

  1. You took the course because it was 10 hours
  2. You took the course because you want to learn Topic A, B, C.

The argument by some students (who haven’t considered it logically) is that: they thought the course was 10 hours, but 2 hours of that was “only” appendix material.

Aside from all the other points I’ve brought up already, this is STILL a very silly idea.


I LOVE learning things fast.

Time is precious. I don’t have any to waste.

If you tell me that I can learn something 20% faster than I previously assumed, I would be overjoyed!

That’s great!

It means I learned what I expected to learn, in less time.

Can someone explain to me why the above doesn’t make perfect sense?

“If you remove the appendix, you can add more material!”

No, this is not how it works.

There’s no time limit for a course.

If I removed the Appendix, it wouldn’t mean adding more material.

I add more material to my courses all the time, without affecting the Appendix.

Where did people get this silly idea?

Again I repeat: the Appendix does not displace any content. It does not hurt you in any way. It is additional material.


Read the course description

Even if you disagree with all the points above (I don’t really see how that could be), who is to blame?

The entire contents of the course are displayed in the course description page before you sign up.

You can see the title of every section, every lecture, and the corresponding durations.

Therefore, if something like 2 hours of Appendix material really bothers you, why in the world did you sign up!?

Ask yourself this question, and then ask yourself if you think I should carry the burden of your mistake (misreading, or not reading at all).


You think you don’t need the appendix, but you do

The reality is, some students don’t think and only assume.

I’ve lost count of how many times students complained about the appendix, yet:

  • Failed to use the Q&A (the #1 rule of “how to succeed in this course”)
  • Failed to do the exercises as instructed
  • Failed to set up their environment correctly
  • Failed to understand the prerequisites
  • Failed to understand the purpose of the course
  • Failed to understand the differences between Python 2 and 3
  • Failed to understand why they don’t need Jupyter Notebook to run Python code
  • Failed to understand my not using Jupyter notebook has no effect on whether they use Jupyter notebook (it’s just Python code, it works the same everywhere)

And the list goes on…

If these students would have stopped complaining, and followed the instructions right in front of their very eyes, they would have fixed their understanding.

Yet they prefer to just complain and not use the advice which actually answers their questions. Why?

Maybe, instead of dismissing the Appendix, it would have been better to pay close attention, and consider: “There must be some reason these questions are asked so frequently, maybe they will help me too”.