What Is Blockchain?

What Is a Blockchain?

A blockchain is a database that stores information in linked 'blocks.' Unlike a regular database owned by one company, a blockchain is shared across thousands of computers worldwide. No single person or organization controls it. Every transaction is recorded permanently and publicly — making it virtually impossible to alter or hack.

How Does a Block Work?

Every block contains three things: the data being recorded, a unique cryptographic fingerprint called a hash, and the previous block's hash. That last part creates the chain — each block is mathematically connected to the one before it. Change an old block and its hash changes, breaking the chain and alerting the entire network instantly.

What Is Consensus?

When a transaction is submitted, thousands of computers independently verify it before recording. This agreement process is called consensus. It makes blockchain trustworthy without trusting any single party — the math and the majority of the network enforce the rules automatically.

What Is Blockchain Used For?

Bitcoin is the most famous use, but blockchain has thousands of applications. Supply chains track products from factory to shelf. Healthcare stores patient records securely. Governments test blockchain voting systems. Financial institutions use it for faster international payments. Smart contracts on Ethereum automate complex agreements without lawyers.

Is Blockchain the Same as Cryptocurrency?

No. Cryptocurrency is one application built on blockchain — just as email is one application built on the internet. Blockchain is the underlying technology. Bitcoin is a cryptocurrency that uses blockchain. Many blockchains have no cryptocurrency component at all.

Can Blockchain Be Hacked?

Bitcoin's protocol has never been successfully hacked since 2009. However, applications built on top — exchanges, wallets, and smart contracts — can have vulnerabilities. This is why wallet security and using reputable platforms is so critical.

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