I'm not a CS major. I've been doing JS for a while and found very few things that I didn't know. One of them, was why some variables remain in scope and some not. I tried searching for answers, but Google is of little help if you don't know what you're looking for.
This word immediately answered what I wanted to know, and the pages linked to even more pages with even more in-depth knowledge not only about JS, but also usability and some cool browser hacks. I had tapped into a higher plane of knowledge.
Forget "open sesame", as "closure" --ironically-- opened more doors for me.