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# What is the Bitcoin Blockchain?
- URL: https://www.tyrinnsikt.no/what-is-the-bitcoin-blockchain/
- Published: 2026-09-23T09:30:02.000Z
- Updated: 2026-09-23T18:18:19.000Z
- Author: TÝR Markets Research
- Tags: Blokkjede

### What is the Bitcoin Blockchain?

Blockchain is simply a chain of transaction history between wallets or accounts. Every Bitcoin that exists today includes a trace or fingerprint, if you like, of all previous transactions—all the way back to the Genesis Block, the first "transaction" made on the Bitcoin network on 3 January 2009\. The transactions are linked through a verification process called block mining. The block includes multiple transactions that are verified by complex mathematical operations to solve cryptographic puzzles.

In short, transactions are verified in **blocks**, and the blocks are linked like in a **chain**, hence the name: **Blockchain**.

### What Makes the Blockchain Secure?

Think of the security in the Blockchain as a never-ending lock that gets slightly longer with each transaction. The lock can only be opened with an encrypted key.

Imagine the encryption like this: Each time a new transaction occurs, a new tooth is added to the key, making it longer and more unique. Every new transaction makes the lock longer; you need a longer and updated new key to access it. The key holds information from all previous transactions, meaning every new tooth depends on the ones before it.

If you try to remove or alter a transaction, it is like filing down or breaking a tooth on the key—the key will no longer fit the lock, and the Blockchain will reject the transaction.

### What Does it Mean to do Bitcoin Mining

The backbone of any blockchain is the miners. Miners verify transactions, secure the network, and serve as the democratic force of the network. They are the source of truth for the blockchain.

When miners verify transactions, they each create a copy of the existing key, add a new "tooth" to it, and generate a new verification key. For the blockchain to remain valid, at least 51% of miners must have the exact same key.

### What Happens If a Miner Tries to Cheat?

If a fraudulent miner tries to manipulate the Blockchain—for example, by creating a fake Bitcoin by rewriting the transaction history—their version of the key will not match other miners' keys. Since the network only trusts identical keys, the incorrect version is rejected, and the corrupted block does not become part of the Blockchain, rendering their fake transactions useless.

### Why Bitcoin Cannot Be Hacked or Stolen

Bitcoin's security comes from the notion that no historical transaction is ever deleted, and every new transaction is related to every old transaction. This key verification process is virtually impossible to hack or steal.

Unlike traditional banks, where hackers can break into a system and move money, Bitcoin's security relies on cryptographic verification and global consensus—there is no single point of failure.

To successfully "hack" or change the Blockchain, a hacker must redo the mining of historical blocks and all the blocks thereafter. The group or individual miner must control 51% of the network, and only then can the other 49% be forced to accept the new altered version of the chain.

It is practically impossible to change historical blocks since millions of miners are constantly verifying transactions, and the more verification a block gets, the more computationally impossible it is to change the history of the Blockchain. The more miners that confirmation a transaction (block confirmations), the exponentially more energy is required to change it.

This is the power of Proof of Work (mining with hardware), and the energy required to verify a Bitcoin transaction is what keeps Bitcoin network safe.

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