Intro to Programming track?

Hi there! I see that some people have badges from a track called "Intro to Programming." Does this track still exist? I am currently working through the Python track, which is enjoyable, but I am approaching the lessons with Python being my very first language experience. :) I understand how to execute things in the sense that I can memorize keywords and function names and remember if I type X, then Y tends to happen. However, I'd love to have a bit deeper understanding of what is going in the background when I execute things. (I'd like to be able to map out the bigger picture in my brain.) For example, what exactly is a "stack," and how does it work? (I'm sure there are other examples, but I don't know enough to come up with them.) Is there a track that addresses this, or would anyone have recommendations as to where I can go to fill in the gaps? Thanks!!