Often when someone asks "What is a blockchain?", he receives an anwser like this one: "The blockchain is a distributed ledger maintained by thousands of computers working together to record and secure all transactions."
This response is certainly true, but in fact it does not allow the newbie to really understand why this invention is so amazing. Even the question "What is it" is a bad one. It is less how it works that matters than why it was created in the first place. The best way to introduce the blockchain is to explain its usefulness.
"WHY?" rather than "WHAT?"
This famous presentation above explains why we should always start with the "WHY". So when asked to explain what it is, instead of explaining how it works or what is it, I give this first simple answer:
A blockchain is a sort of database that allows the creation of non duplicable digital information (that we call digital asset).
Then I develop a bit more without diving into technical stuff: "Think about it. Until 2009 (date of creation of Bitcoin), almost all the information we exchange through the Internet are 'duplicable information'. Pictures, text, music, everything that we store in our usb keys, hard drives, cloud servers can be easily copy/paste and multiply perfectly. It is after all only a succession of 0 and 1.
But in 2009, Satoshi Nakamoto created the first digital information that is not duplicable. In other word, you cannot copy/paste a bitcoin to have more, and if I send you one bitcoin, at the moment you receive it, I will loose it. That my friend was not possible before Bitcoin."
It is only after I gave this first introduction that I will explain how this technical 'tour de force' is possible and explain a bit more how a blockchain works. What I said above may seem trivial for you, but believe me most of people are not aware of this simple aspect of this technology.
