A blockchain is a decentralized database that consists of consecutive blocks of data. Each block is linked to the previous one through a cryptographic signature. This ensures transparency, security and the impossibility of changing data after it has been added. Here are the main principles of blockchain:

1. Blockchain structure

• Blocks: Each block contains data (transactions or other information), a hash (cryptographic signature), and a hash of the previous block.

• Chain: Blocks are connected in series. Changing data in one block affects all subsequent ones, making the system tamper-resistant.

2. How blockchain works

• Transaction: Users send requests to add data (e.g., transfer funds).

• Verification: The network verifies these transactions. This is done through a consensus mechanism.

• Block formation: After verification, transactions are collected into a block.

• Adding to the chain: A new block is added to the chain and becomes part of the data history.

3. Cryptography

• A hash is calculated for each block. This is a unique code that is generated based on the data in the block. If the data changes, the hash changes as well.

• The hash of a block always includes the hash of the previous block, linking them into a single chain.

4. Decentralization

• Copies of the blockchain are stored on many computers in the network (nodes).

• There is no single control center, so no one can control the blockchain alone.

5. Consensus mechanisms

To reconcile data between network participants, consensus algorithms are used:

• Proof of Work (PoW): Participants (miners) solve complex mathematical problems to add a block.

• Proof of Stake (PoS): Blocks are created based on the share of cryptocurrency a participant holds.

6. Advantages of blockchain

• Security: It is impossible to change information without the consent of the entire network.

• Transparency: Data is available to all participants.

• Independence: Lack of a central authority.

7. Application

• Cryptocurrencies (Bitcoin, Ethereum).

• Logistics and supply systems.

• Voting.

• Smart contracts.

Blockchain is not only the basis of cryptocurrencies, but also a promising technology for many areas.