Ever wondered what a Bitcoin block really is?
Or what exactly miners are doing when they “mine” Bitcoin?
Let’s break it down:
A block is a container of verified Bitcoin transactions and miners are the ones who build and secure them.
The moment a new valid block is found, every mining pool immediately adds it to its local copy of the blockchain. Then, the ruthless race for the next block begins instantly.
Mining pools first broadcast an empty block template to all their miners; this allows them to start computing right away, without waiting to collect transactions.
Once the pool selects the most profitable transactions from its mempool, it replaces the empty block with a tentative block containing those transactions. If no one has yet found a valid block, the miners switch and continue working on this new version.
But what are they really doing?
They’re running a specific cryptographic calculation and comparing the result to a value called the difficulty target.
If the result is below that target, meaning the calculations were “hard enough” to prove substantial work, the block is valid.
That’s the essence of Proof of Work: energy and computation turned into digital trust.
Currently, the miner or mining pool that finds the next block receives a 3.125 BTC reward, plus all transaction fees. This reward halves every four years, a built-in mechanism that makes Bitcoin increasingly scarce over time.
But here’s something you might not know:
What happens when two miners find valid blocks almost at the same time?
It actually happened in January 2021.
Two mining pools, Slushpool and F2Pool, each found a different but valid block within seconds.
Both versions propagated across the network, and miners around the world split; some built on Slushpool’s chain, others on F2Pool’s.
Then came the tie-breaker.
A miner on Slushpool’s side found the next block first, making its chain longer and therefore the official one.
F2Pool’s block? It became what’s called an orphan; a valid block that didn’t make it into Bitcoin’s final history.
These “one-block reorgs” happen 3–4 times a year.
But the last time more than one block was orphaned in a reorg?
That was back in 2010, 15 years ago!
This is how Bitcoin quietly self-corrects in real time, with no central authority needed.
Just code, consensus, and incentives doing their job.
At OffChain Luxembourg, we believe that understanding these mechanisms is key to building trust in crypto!
If you want more insights like this, join one of our events or check out offchain.lu to receive updates on the courses!
Here, we’re learning together! 🧡
