Oh, and callbacks definitely exist in other languages, like C.
What's the deal with this trend of setting up a whole website for a (basic) blog post?
"Simple concept" is subjective. I'd bet that discussing "simple concepts" with an engineer or scientist would likely cause your mind to grasp and instinctively try to relate to your own memorization of facts. But that shouldn't preclude you from discussing what you do know, or for that matter, sharing it with the world.
Yeah you're probably right, I've been a bit pedantic.
I feel this article is unnecessary long for the subject, it would be a good length for something like "setting up a hadoop cluster", but having all sorts of articles about all subjects is a very good thing. My bad.