"The last question:

Node.js is important because
 A. It is compute-bound
 B. It is I/O-bound
 C. It supports greater concurrency
 D. All of the above.

is quite confusing. The reading states that Node.js utilizes event loops to achieve high concurrency and that it handles I/O bound http requests while it's not great at handling compute-bound requests. This questions is quite broad and confusing."

Why is it harder to increase disk speed than it is to increase CPU/processor speed?

I'm still a bit confused on how callbacks work. Can you show additional examples in class? 

I am still a bit confused about what exactly an event loop is. How do they allow for concurrency/how is this different than threads?

I still don't really understand the workings behind blocking and non-blocking, despite know their impacts... Could you expand on the two please?

I'm confused on concurrency. Can you clarify concurrency? Can you explain why Nginx is so much faster if it is using only one thread? If nginx is so much faster than Apache, why use multithreading?

What does it mean for a language to compile to JavaScript?

What causes ""callback hell""?

How could you use node.js with MySQL? 

I'm still confused on this idea of waiting - we say that Node.js is good because there's no thread waiting for some code to finish executing, but in Node.js, is the callback function also not waiting for some event to happen? Or does the callback function not take up space the way a thread does?