Now, when you swipe your card a third-party validates that transaction. This is usually done by banks or credit card issuers. Since blockchains have no third-party validators, transactions are confirmed through people all over the world called "miners". These miners have specialized computers that confirm transactions as they are placed in the blockchain. Since the blockchain is held in every miners computer, each time new transactions are published, every miner can see that block. Once the block is posted all the miners get to work to try and find the puzzles solution. Once a solution is found it is posted to the blockchain for the other miners to validate. The winning miner is rewarded in cryptocurrency and the next block is posted for the process to start over. This guarantees an incentive for people to mine as well as a key security feature that requires consensus among the community. If a fraudulent block was posted, the entire community would see that it is not valid and throw it out. This is why some cryptographers believe the blockchain is resistant to hacking.
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