In the previous section, we learned how a block’s hash is calculated. But there’s a fundamental difference between obtaining any hash and finding one that meets Bitcoin’s requirements.
To add a new block to the chain, it’s not enough to calculate its identifier. The result must meet a mathematical condition: it must be less than or equal to a threshold set by the protocol, known as the target.
And how do you get that result?
Miners perform a huge number of calculations, modifying certain data in the header and applying the SHA-256 cryptographic function twice again.
Each modification produces a new hash that must be compared with the required target.
If it does not meet the condition, the process is tried again with different data.
But the interesting thing is that nobody can predict which attempt will produce a valid hash.
There is no known formula that can directly reveal the solution. The results are unpredictable before they are calculated, and each new attempt has an extremely small chance of success.
That is why we say mining is a probabilistic process....
Imagine thousands of specialized computers around the world, continuously performing extraordinary amounts of calculations. They are all searching for a result that meets Bitcoin’s conditions.
One miner might find it on their next attempt, while another might perform trillions of calculations without succeeding.
And this brings us to the explanation for the famous ten minutes.
Bitcoin does not necessarily produce a block every ten minutes. That time is an average the protocol aims to maintain.
A block might appear just a few seconds after the previous one. Twenty, thirty minutes, or more might also pass without a single block being found.
Each new attempt is another chance to succeed, but having waited a long time does not mean the next calculation is more likely to work.
So how does Bitcoin maintain that average when the number of participating computers is constantly changing?
Through a mechanism called difficulty adjustment.
Every 2,016 blocks, or approximately every two weeks, the protocol readjusts the mining target based on how long it took to produce the blocks in that period.
If they were found too quickly, the difficulty increases. If they took too long, it may decrease.
In this way, Bitcoin adjusts the mathematical challenge without setting fixed schedules or relying on a central authority to decide when the next block should appear.
However, finding a suitable hash is only one part of the process. The block must also comply with Bitcoin’s other rules and be verified by the network’s nodes.
And this brings us to a fundamental question: if a miner finds a new block anywhere in the world, how does that information reach the other computers so they can verify it?
To understand this, we need to learn how communication between Bitcoin participants works....
Shall we see???