Exactly What Are Prohormones?

First of all. Yes I’ve used the search function and read up all I could about prohormones. However, since most threads were written up with a rather “theoretical” POV or by some dude trying to sell stuff… I’d MUCH rather get the opinion of the knowledgeable and first hand-experience guys here.

Could someone explain to me exactly what these are? Specifically, epistane, which has been subject of much talk lately.

As far as I know, Prohormones, act like AAS, but are completely different chemically. Correct?

What is the difference between prohormones and AAS? Are they cheaper? Safer (not that I’m really afraid of the bullshit propaganda saying AAS are dangerous as hell)? Are some illegal in America?

From what I’ve seen, most of them are oral. This presents some big problems (as the liver destroys the compound most of the time). Are there any injectable PHs?

Any recommendations?

Damn that is a lot of questions.

Thanks.