It happens all the time:

• I try to read an article or a paper on a programming technique, say B-Trees
• I read and understand the first few pages about motivation behind the technique and other expositions
• when it comes to the details, my eyes start to glaze over, I read but I rarely understand

I end up being aware of techniques, but not really understanding them at the same level I understand linked list (which I’ve implemented many times in my programs). The time I spent reading the paper feels wasted.

For example, I’ve read about skip lists several times in the past but today is the first time I can say that I understand skip lists well enough to implement them. Why? Because today I have actually implemented them.

You have to implement to truly understand.