For some time now, the term blockchain has been emerging on the web and elsewhere, but it is not always easy for some to have a clear idea of what it represents.

The idea of construction and operation is quite simple.

The latter is a means of transmitting, storing, and verifying information in a mathematical and entirely decentralized way.

Let us take a notary as a counter-example. The latter is a trusted and recognized individual who confers (in exchange for payment) on the acts you ask for a pledge of authenticity through his signature.

However, everything is based on this so-called trust that you and others have in him and without which the acts would no longer be of any value. Not only is it theoretically possible for him to lie and validate a litigious act, but it is also conceivable for other individuals to copy his seal and signature to authenticate forgeries.

A revolutionary technological breakthrough

The way the blockchain works is revolutionary in the sense that no trusted third party is necessary and falsification of acts is impossible. The blockchain network is made up of multiple individuals called miners (now several hundred thousand) who are responsible for validating the latter which are in a block by mathematical proof. Once the block is approved, it is linked to the previous ones.

It is not possible for minors to falsify a transaction because, as a result of decentralization, if one of them decides to lie by validating an illegal operation, the others will invalidate it later. Each person can play the role of the miner, thus guaranteeing the neutrality of the network.

Nor is it feasible for a person to do an invalid act as something that is validated because the blocks containing the authentic acts are visible to all. Indeed, each person participating in the network downloads all the blocks (and therefore the acts) since the creation of the network.
Miners get blockchain transaction fees that each person who wishes to enter something in the blockchain must pay (the average fees are generally meager, the equivalent of $0.05 for some cryptos), but also by creating new tokens (or cryptocurrencies) that they can then sell. Indeed, it is the latter that will be used to pay future transaction costs.

Multiple applications of the blockchain are possible, the most famous being its use for crypto-currencies. The first application of the blockchain is bitcoin.

Operation in summary:

1. Jane wants to send 1 Bitcoin to John. She deposits her transaction in a pool (which contains all transactions pending validation) and deposits a “tip” (transaction fee) for minors.
2. Miners select from the pool the transactions with the most tips and then put them in a block.
3. The block is then validated using cryptographic means thanks to the work of the latter. They receive tips and new coins created during this process (ensuring the circulation of new cash).
4. The block is registered in the blockchain, and anyone can, therefore, see the transactions present in this block (unless the blockchain is private).
5. John received his Bitcoin because the network validated Jane’s shipment and entered “+1 BTC” in John’s wallet.

Of course, an infinite number of applications are conceivable, such as a decentralized supercomputer, a secure cloud, or even a new Internet. The operation described above will remain the same if blockchains with a different security principle, the Proof-Of-Stake, are introduced. We will not be interested in it in this article.