A blockchain is a digital record-keeping system where information is stored in connected blocks, with each block containing a list of transactions. Once information is added to a block, it becomes very difficult to change because it is linked to all the blocks that came before it. Many cryptocurrencies use blockchain technology to keep track of who owns what.
Imagine a notebook where you write down every time someone sends money to someone else. Instead of one person keeping the notebook, thousands of computers each have a copy, and they all must agree before a new transaction is added. This makes it nearly impossible for anyone to cheat by erasing or changing old entries.
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