Note: this article is for some parts a bit technical, but you can skip those parts and just read the plain text, which is supposed to be understandable by anybody
Note2: for Ethereum some sections are copy/paste from articles and Ethereum official documentation
The intent here is to explain what is really behind the crypto currencies technologies which is never really explained and people don't know unless they have some (kind of deep) technical knowledge
I often react when people are talking about crypto currencies as "virtual" money, this is not virtual money but electronic money, there is a work behind this and this is no more virtual than a bank bill
Now, when it comes to discuss sidechains and smart contracts, things can really become virtual, let's see how it works on bictoin and ethereum, for comprehension purposes we have to go a little far in technical details while using some simplification language as some experts might notice and start with easy things, this is not a vulgarization arti