Imagine that you are part of a group of 100 people who, due to a bizarre plane crash, end up on an island that does not appear on the map. You are incommunicado with the rest of the world and there is no means of transport to get you out of there. You will probably be there for a long time, so you decide to set up a partnership on this island.
But you know from experience (and also because this story of a plane crashing on a lost island is eerily familiar) that a society needs leaders. But a governance structure generates power struggles that can turn into serious conflicts. So you decide to design a different model of society: everything that happens there needs to be approved by the whole group, so that what is true for one will have to be true for the others.
And how is this done? From a log book someone brought on the plane. This same person explained that this book is magic: it is possible to create infinite copies of them, but everything that is registered in it will automatically be registered in the others.
So the copies will be the same forever. Due to this feature, you decide to create a copy of the book for each person. Since this book cannot be erased or tampered with, it becomes an essential part of a system that distributes resources fairly and efficiently on the island. Everything that is recorded in the book is valid for everyone, as the records appear in all units.
This book came to be called a blockchain .
the meaning of blockchain
Let’s get back to the “real world” (or the non-fiction world, if you prefer). Understand such a society on the island as the Bitcoin platform, and the magic book as, in fact, the blockchain. The difference is that the real blockchain isn’t magic: it’s a sophisticated computer system.
Since we’re talking about a distributed database system and no middlemen, we need a reliable mechanism to allow direct transactions — peer-to-peer. This is the role of the blockchain.
The blockchain is a system of record that contains all transactions processed on the system. In free translation, the name means chain of blocks . A chain of blocks is nothing more than a set of registered information that is linked to previous and successor blocks of information.
These blocks of information are also public, in the sense that all nodes (participants) in the network have access. However, when processed, blocks cannot be deleted or changed. Furthermore, new registrations can only be made through a validation process.
This system, because it is distributed, is on thousands of computers. When a (legitimate) update is made, all copies are synchronized in a matter of seconds. It may even be that one or the other computer disappears from the network, but this will not affect the system, as all the other nodes are still there.
To certify information in a chain of blocks and prevent fraud, the blockchain has a mechanism called proof of work — proof of work , in direct translation. It is a cryptographic protocol that validates a transaction on a computer (or other device) by solving a mathematical problem.
Tampering with block chains, however small, will yield different results than expected for this mathematical problem. This prevents the transaction from being processed and, consequently, its registration. We will study this aspect in more detail later.