Simply put, a ledger that keeps track of all bitcoins and their movements. All movements can be traced back and everyone has access to them. So it’s an open ledger. At the same time, then, it is the most powerful computer in the world It is estimated that in order to surpass the computing power of the Bitcoin blockchain network, every person on the planet would need to have 300 average computers, all working on it. Well, it sounds incredible, but it’s true.
The public nature of all bitcoin transactions is also, to me, the main argument for why bitcoin will never be used for criminal activity on a large scale. Really, only a fool would do that.
This computing power is used by the network to verify transactions, and miners then receive rewards in the form of mined blocks. The rewards are halved approximately every 4 years. Another source of rewards for miners are fees from transactions made, on the bitcoin network.
Thanks to the blockchain, Bitcoin is the most secure and powerful payment system ever.
The verification itself for BTC is then called proof of work, or proof of work. There is another principle that other cryptocurrencies use, which is proof of stake.