What exactly is this blockchain thing, anyway?

“One cause of confusion is the phrase the blockchain, which makes it sound like blockchain is one specific thing. In reality, the word blockchain is commonly used to describe two broad types of computer systems. Both use similar underlying protocols, but they have other important differences. Bitcoin represents one approach to using blockchain, one wedded to principles of radical decentralization. The second approach—pioneered by more business-minded players—puts blockchain to use without adopting bitcoin’s revolutionary, decentralized governance. Both of these designs are short-handed as blockchains, so it’s easy to miss the crucial differences.”

Source: There is no such thing as “the” blockchain.

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