Blockchains are secure because no single party controls the network.
But what if one group gained too much power?
That’s where a 51% attack comes in.

💥 What Is a 51% Attack?

A 51% attack occurs when a group of miners or validators controls more than 50% of a blockchain’s computing power (hash rate) or staking power.

With that majority, they could:

🌀 Reverse recent transactions

💸 Double-spend coins

🚫 Prevent new transactions from being confirmed

It’s like rewriting blockchain history — very dangerous for trust and security.

🔍 Why 51%?

Because blockchains rely on consensus — if more than 50% agree, it’s accepted as truth.
So if one group has the majority, they can manipulate that truth.

🧠 Simple Analogy:

Imagine a voting system with 10 people. If 6 people team up, they can decide the results unfairly, even if it’s wrong.
That’s what a 51% attack looks like in crypto.

🛡️ Is It Common?

Not on major blockchains like Bitcoin or Ethereum — they’re too big and expensive to attack.
But smaller blockchains are more vulnerable due to lower hashrate or validator count.

📚 References:

  1. Binance Academy – 51% Attacks Explained

  2. Investopedia – What Is a 51% Attack?



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