Blockchain is the technology underpinning Bitcoin and most cryptocurrencies. Simply put, a blockchain is a special digital ledger that is distributed among many computers worldwide and is virtually impossible to tamper with. This is one of the key concepts to learn in our miner’s glossary.
To understand its essence, you don’t need to be a programmer. It’s enough to imagine an ordinary notebook where we record who transferred how much money to whom. But this notebook has several magical properties.
Analogy: A Shared Notebook for the Entire Building
Imagine that all residents of your building decided to give up cash and keep track of all transactions in a shared notebook. To ensure no one cheated, they agreed on several rules:
- Everyone has a copy. Each resident has an exact copy of this notebook. When someone makes a new entry (e.g., “Ivan transferred 100 rubles to Masha”), everyone else also records it in their notebooks.
- Entries are permanent. You cannot tear out a page or cross out an old entry. You can only add new ones.
- All entries are public. Anyone can view the entire transaction history and verify that Ivan had those 100 rubles to transfer.
- Entries are “sealed.” Each new page (block) is “glued” to the previous one using a unique cryptographic “seal” (hash). If someone tries to change an entry on an old page, the “seal” will break, and all other residents will immediately see this and reject the forgery.
This is what blockchain is. It’s a system where many participants store an identical, constantly updated, and securely protected database.
Three Key Properties of Blockchain
From this analogy, three main advantages of the technology emerge:
- Decentralization. There is no single central authority that stores the “master” notebook. Everyone has copies, so destroying or capturing one computer is pointless. The system will continue to operate. This makes it incredibly resilient.
- Immutability. Thanks to the cryptographic “gluing” of blocks, it’s virtually impossible to change information in an already recorded block. This would require rewriting all subsequent blocks on thousands of computers simultaneously, demanding colossal computational power.
- Transparency. Most blockchains (including Bitcoin) are public. Anyone can view all transactions that have ever occurred on the network. However, users’ personal data remains anonymous – only wallet addresses are visible.
How Does Blockchain Work Using Bitcoin as an Example?
In the Bitcoin network, this technology is supported by miners. They perform the very “work” we discussed in the article about Proof-of-Work.
Miners gather new transactions into a “candidate” for the next page (block) and then compete to be the first to find that unique “seal” (hash) for it. The one who finds it first earns the right to add the block to the overall chain and receives a reward for it. After this, all other network participants verify the new block, ensure its correctness, and add it to their copies of the blockchain.
This technology allows people who don’t know or trust each other to conduct financial transactions directly, without intermediaries like banks or payment systems, with confidence in the reliability and security of these operations.
