What is Blockchain?

Blockchain is a distributed log technology that acts as a public and immutable digital reason book. Each block contains a set of verified transactions, and all blocks are encrypted, forming a continuous and inviolable stream.

Think of blockchain as a notebook where every page is a block, every note is a transaction, and once written, no one can delete or change it.

How does it work in practice?

When someone makes a transaction on a blockchain (sending Bitcoin, for example), that transaction is transmitted to a network of computers called nodes.These nodes verify the transaction using consensus algorithms, and once approved, it is recorded in a block along with other transactions.

Each block contains: the transactions, a timestamp, a hash (cryptographic fingerprint) and the hash of the previous block.This creates a chain where changing any block would invalidate all subsequent blocks.

Decentralization: the central concept

Unlike a bank or government that controls a centralized system, blockchain isined by thousands of computers around the world. There is no single point of failure. To hack a blockchain, it would be necessary to control more than 50% of the entire network simultaneously, something practically impossible in large networks like Bitcoin.

Mechanisms of consensus

In order for all nodes to agree on which transactions are valid, there are different consensus mechanisms:

  • Proof of Work (PoW)Miners solve complex math problems. Used by Bitcoin.
  • Proof of Stake (PoS)Validators bet their currencies as security. Used by Ethereum.
  • Delegated Proof of Stake (DPoS)Holders vote on delegates. Used by Solana and EOS.

Types of Blockchain

Publicly :Anyone can participate (Bitcoin, Ethereum). Totally decentralized and transparent.

and private:Controled by an organization. Used by companies for internal use cases.

The hybrid:It combines elements of both, allowing partial control with selective transparency.

Applications Beyond Cryptocurrencies

Blockchain goes far beyond digital money. It is used in smart contracts, NFTs, supply chain, digital voting, decentralized identity, medical records and more. Any system that needs transparency, immutability and trust can benefit from this technology.

Current Restrictions

Despite the potential, blockchains face challenges such as scalability (limited transactions per second), energy consumption (in PoW networks), gas costs and complexity for ordinary users. Solutions such as Layer 2, sharding and new consensus mechanisms are being developed to address these limitations.