New entries are grouped into blocks, and each block carries a cryptographic fingerprint of the one before it. Change anything in an old block and every fingerprint after it breaks, which makes tampering easy to detect and effectively impractical.
Because thousands of participants each keep a copy and agree on updates by fixed rules, a blockchain needs no central administrator. This is the technology that lets Bitcoin, Ethereum and most crypto assets exist without a bank or company in charge.
What Is Crypto and Blockchain? A Plain-English Start
Key takeaways
- A blockchain is a shared record that many computers keep and agree on together.
- Linking each block to the last makes rewriting old history impractical.
- No single company runs a public blockchain; the network enforces the rules.
Blockchain — perguntas frequentes
Is every blockchain public?
No. Many are open for anyone to read, but some are private or permissioned and controlled by specific organisations.
What stops someone faking a transaction?
Cryptographic signatures and network-wide validation mean invalid entries are simply rejected by everyone.
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