Blockchain Technology: Fundamentals and Applications

Actualizado: 2026-05-03

Blockchain is a distributed database that allows digital records to be created that no participant can unilaterally alter, without needing a central authority to validate them. Born in 2008 as Bitcoin’s infrastructure, the technology has transcended cryptocurrencies to find application in supply chains, medical records, legal contracts, and electronic voting. Understanding how it actually works — beyond the media noise — is the starting point for evaluating when it makes sense to use it.

Key takeaways

• Blockchain is a chain of data blocks cryptographically linked, replicated across a network of nodes that validate transactions through consensus mechanisms.
• Practical immutability comes from the fact that modifying a block requires recalculating all subsequent blocks and convincing the majority of the network.
• The two most widespread consensus models are Proof of Work (PoW) — energy-intensive — and Proof of Stake (PoS) — more efficient.
• Smart contracts are code that executes automatically on the blockchain when predefined conditions are met.
• Its applications with the most real traction are cryptocurrencies, supply chain traceability, and asset registration.

How blockchain works

The data structure is simple in concept: a block contains a set of validated transactions, the hash (cryptographic fingerprint) of the previous block, and its own hash. By linking each block to the previous one via hash, a chain is created where any modification to a block invalidates all subsequent blocks.

The network consists of nodes (computers) that maintain a full or partial copy of the chain. When someone proposes a new transaction, nodes verify it and add it to the next block via a consensus mechanism:

• Proof of Work (PoW): nodes compete to solve a computationally expensive mathematical problem. The winner proposes the block and receives the reward. Bitcoin uses PoW. Its energy cost is its Achilles’ heel.
• Proof of Stake (PoS): validators propose blocks in proportion to the assets they have locked as collateral. Ethereum migrated to PoS in 2022 with The Merge, reducing its energy consumption by 99.95%.

Decentralisation is the key value: no individual participant controls the network. This eliminates the risk of a central authority manipulating records, but introduces the complexity of coordinating consensus among thousands of mutually untrusted nodes.

Smart contracts and Ethereum

The most relevant innovation after Bitcoin was Ethereum, which added to the blockchain the ability to execute smart contracts: programmes stored on the chain that execute automatically when predefined conditions are met.

A smart contract can represent:

• A fund transfer conditional on the recipient delivering a digital asset.
• The automatic issuance of a token when a funding threshold is reached (ICO, crowdfunding).
• The settlement of a financial derivative based on external oracle data (market price).
• Governance rules for a decentralised autonomous organisation (DAO).

Smart contracts are irreversible — the code executes as written, with no possibility of subsequent human intervention — making them powerful but also dangerous if they contain errors. The 2016 DAO hack, which resulted in the loss of $60 million in Ether, is the best-known case of a smart contract exploited through a code vulnerability.

Applications with real traction

Cryptocurrencies and DeFi Bitcoin and Ethereum are the most mature and widely adopted applications. Decentralised finance (DeFi) builds lending protocols, asset exchanges, and stablecoins on smart contracts without banking intermediaries. The total value locked in DeFi reached peaks of over $100 billion, though with high volatility.

Supply chain Product traceability from origin to end consumer is one of the use cases with the most documented ROI. Walmart uses a blockchain (based on private, permissioned Hyperledger Fabric) to track fresh produce: in case of contamination, it reduces origin identification time from days to seconds. Maersk and IBM developed TradeLens for international trade documentation, though the project was discontinued in 2022 due to adoption difficulties among competitors.

Asset registration Several countries (Georgia, Honduras, Sweden) have experimented with blockchain for real estate registries. The advantage is transparency and resistance to corruption; the challenge is system governance when a human error arises that needs correction.

When blockchain makes sense and when it doesn’t

The most useful question before adopting blockchain is: do I actually need decentralisation? If the answer is no — if there is a trusted intermediary that can manage the record — a conventional relational database is more efficient, faster, and cheaper.

Blockchain adds genuine value when:

• Multiple parties that don’t trust each other are involved and none wants another to control the record.
• Public auditability is required without revealing identities.
• Record immutability is critical (legal records, chain of custody).

It doesn’t add value when:

• A single organisation controls all the nodes (in that case, it’s just an expensive database).
• Data needs to be modified or corrected frequently.
• Transaction speed is critical (Bitcoin processes ~7 TPS; Visa processes ~1,700 TPS).

The same discipline of thinking about the problem before choosing the tool applies here, just as when choosing an AI model for B2B sales optimisation: the technology is not the starting point — the problem’s requirements are.

Conclusion

Blockchain brings decentralisation, transparency, and immutability to digital records, and that has real value in contexts where these properties are necessary. Cryptocurrencies and supply chain traceability are the most proven cases; smart contracts remain an active development area with significant implementation risks. The most common mistake is applying blockchain to problems that a centralised database would solve better, cheaper, and faster.