What is blockchain technology?

Definition of blockchain technology

Blockchain is a decentralized digital ledger that records transactions across a network of computers in a way that’s transparent, secure, and nearly impossible to alter. Where traditional databases are usually controlled by a central authority, blockchain uses a distributed system where each participant holds a synchronized copy of the ledger. This decentralization eliminates the need for intermediaries and reduces the risk of data manipulation or single points of failure.

Each transaction on the blockchain is grouped into a ‘block’ and added sequentially to a growing chain of previous transaction records. These blocks are linked together and secured using cryptographic hashes. This means that once data is recorded, it can’t be changed without the network’s approval.

There are three key features to blockchain technology:

• Decentralization: In a blockchain, control and decision-making is distributed across the network rather than being managed by a single entity. Every participant (or ‘node’) maintains a copy of the blockchain for maximum transparency.
• Immutability: Once a transaction has been recorded, it is immutable (cannot be altered). If there are any errors, they need to be corrected with a new transaction that becomes part of the permanent record.
• Consensus: Transactions are only added to the blockchain when the majority of nodes in the network agrees that they’re valid.

One of the key benefits of blockchain technology is that it provides security, transparency, and trust without the need for traditional intermediaries like banks or other financial institutions. The way it has been designed helps reduce fraud and errors, making it especially valuable in industries where data integrity and transparency are essential, such as finance and healthcare.

The structure of blockchain

Blockchain technology organizes data into ‘blocks’ that form a continuous ‘chain’, hence the name ‘blockchain’.

Blocks

Blocks are essentially containers of transaction data. Each block includes:

• A batch of validated transactions
• A unique cryptographic hash (digital fingerprint of sorts)
• The hash of the previous block.

The first block in any chain is known as the ‘genesis block’ and each new block is added to the top of the chain. The result is a secure and traceable ledger of activity. If you were to make even one small change to a block, it would invalidate its hash and the hashes of any blocks that follow. This would break the chain and alert the network to tampering.

How new blocks are added

Because blockchain files are distributed across a network, you need consensus to add a new block. Each computer (node) in the network must agree that the new block is valid before it’s accepted. The process of doing this varies depending on the blockchain’s consensus mechanism:

• Proof of Work (PoW): In PoW, computers add new blocks by solving complex mathematical puzzles. This method is energy-intensive but highly secure. Bitcoin uses a PoW consensus mechanism.
• Proof of Stake (PoS): In PoS, nodes are chosen to validate new blocks based on the amount of cryptocurrency they hold and commit (or ‘stake’). This method is more energy-efficient and used by more modern blockchain technologies.

When a block has been validated, it’s added to the blockchain and broadcast to the network. The node which validated or ‘mined’ the block is rewarded with either newly minted tokens (i.e. Bitcoin) or transaction fees.

Decentralization

One of the key features of blockchain technology is its decentralized nature. Instead of relying on a central server, blockchain data is stored across thousands of nodes. Each participant maintains a copy of the ledger and no single party has control over the system, eliminating some of the risks that come with centralized data.

Some of the benefits of decentralization is that tampering is made extremely difficult, there can be no central point of failure, and no user is ‘trusted’ more than the other – all can verify transactions.

How does the blockchain work?

Let’s take a look at each step in the blockchain process.

Record transactions as blocks

Every transaction on a blockchain is captured as a block of data. These blocks store key information about the type of asset exchanged (i.e. tangible or intangible), the parties involved, time and date, and any specific terms or conditions tied to the transaction (e.g. temperature readings for food shipments).

Each block is digitally timestamped with the exact moment the transaction was added to the blockchain. This ensures that transactions are recorded in chronological order, leaving behind a verifiable audit trail while also preventing retrospective alterations.

Connect blocks together

Each block is connected to the one before and after it through a cryptographic hash. The hash is created using data from the previous block as well as the current block, making it almost impossible to change any block without invalidating every block that comes after it. This reinforces integrity and trust throughout the entire system.

Build an irreversible blockchain

When new transactions are verified, they’re added to the blockchain in an irreversible sequence. Each new block strengthens the security and validity of the previous one, making the chain increasingly secure over time. This makes the blockchain tamper-proof and helps prevent fraudulent transactions.

Ensure trust and immutability

Because the blockchain becomes more secure with each new block, it’s nearly impossible to change a transaction that’s already been recorded and verified. This immutability creates a trusted, shared source of truth that ensures all transactions are accurate and unchangeable.

Types of blockchain networks

The four main types of blockchain networks are public, private, hybrid, and consortium networks.

Public blockchain networks

Public blockchains are open to anyone. As long as you have an internet connection, you can view the ledger, submit transactions, and participate in validating blocks using PoW or PoS consensus mechanisms. Bitcoin and Ethereum are two examples of public blockchains.

Public blockchains offer full decentralization and transparency, but they also have certain drawbacks like high energy consumption (for PoW-based systems), lack of privacy, and potentially weaker security.

Private blockchain networks

Private blockchains are permissioned and controlled by a single organization. You can only join if you have been invited and approved by the network administrators. Private blockchains offer greater control over access and governance, making them more common for enterprise applications or internal use.

However, since one organization governs the network there’s reduced decentralization and less resistance to censorship and tampering.

Hybrid blockchain networks

Hybrid blockchains combine the features of both public (decentralized) and private (centralized) networks. Some data might be open and accessible to the public while other information is kept private and controlled.

Consortium blockchain networks

Consortium blockchains are permissioned networks governed by a group of organizations rather than a single entity. These organizations share the responsibility of managing the blockchain, validating transactions, and controlling access. Two examples of consortium blockchains are Hyperledger and Quorum.

Blockchain protocols and platforms

Blockchain protocols are rules that govern how data is recorded, shared, and secured within a network. They define how blockchain users agree on transactions (consensus), how data is structured, and how the system maintains integrity without a central authority.

Blockchain platforms are built on top of these protocols. They provide the infrastructure, tools, and frameworks for developers to build decentralized applications (dApps) and custom blockchain solutions. So while blockchain protocols define the core functionality, platforms turn this functionality into practical solutions.

Here are some of the most widely used blockchain protocols and platforms:

Hyperledger Fabric

Hyberledger Fabric is a modular, open-source framework developed by the Linux® Foundation for enterprise use. It includes a suite of plug-and-play tools and libraries that can be used to develop private blockchain applications quickly, including unique identity management and access control features.

Some use cases of Hyperledger Fabric include supply chain tracking, trade finance, loyalty programs, and clearing asset settlement. It's currently used to power IBM’s Blockchain Platform.

Ethereum

Ethereum is a decentralized, open-source blockchain that can be used to build and deploy smart contracts and decentralized applications. It was specifically designed for business use cases, such as decentralized finance (DeFi) or automation.

Corda

Corda is an open-source blockchain platform designed for highly-regulated industries like finance, healthcare, or supply chain management. Its focus is on privacy and regulatory compliance, allowing businesses to share data and agreements with only the relevant parties.

Quorum

Quorum is an enterprise-focused, open-source platform built on Ethereum. It supports permissioned networks with added transaction privacy and faster consensus mechanisms, allowing companies to execute smart contracts and transact within a secure network.

The evolution of blockchain technology

The origins of blockchain technology go way back before bitcoin, to the 1970s when computer scientist Ralph Merkle patented Merkle trees, a data structure that uses cryptographic hashing to link records together securely. This technology laid the groundwork for blockchain systems.

In the 1990s, Stuart Haber and W. Scott Stornetta introduced a tamper-proof system for timestamping digital documents using Merkle trees, essentially marking the first real-world use of blockchain principles.

Since then, blockchain has continued to evolve over three generations:

First generation – Bitcoin and other virtual currencies

The first true blockchain emerged in 2008 with the launch of Bitcoin, created by an anonymous figure (or group) known as Satoshi Nakamoto. Bitcoin’s blockchain was designed as a decentralized, peer-to-peer ledger for digital payments, eliminating the need for a trusted central authority like a bank.

Bitcoin set the standards for blockchain’s core principles of transparency, immutability, and decentralization. It also solved the problem of double-spending, which was a real issue for digital currencies at the time.

Second generation – smart contracts

The second generation of blockchain started with the development of Ethereum in 2015. Ethereum expanded blockchain’s capabilities by introducing smart contracts – digital contracts that self-execute when certain conditions are met.

This development moved the blockchain beyond just payments and into real-world applications like finance, real estate, supply chain management, healthcare, and even voting systems.

Third generation – the future

Today, blockchain is entering its third generation, focused on solving issues related to scalability, energy-efficiency, and integration with emerging technologies such as artificial intelligence (AI) and the Internet of Things (IoT).

According to Statista, blockchain technology is expected to continue growing, generating nearly $1 trillion USD in economic value by 2032 with a compound annual growth rate of 56.1% since 2021.

Benefits of blockchain technology

The main benefits of blockchain technology are security, efficiency, trust, automation, and traceability.

Advanced security

Blockchain technology provides a high level of security and trust by requiring all data to be verified through a network-wide consensus before being added to the ledger. Once a transaction has been recorded, it becomes immutable, which means it can’t be altered or deleted – even by system administrators. This design eliminates the risk of unauthorized tampering and removes any single points of failure.

Improved efficiency

Business transactions can be slow and create operational bottlenecks, especially if third parties are involved. Blockchain’s transparency means that all parties can access the same data in real time, reducing the need for duplicate records or time-consuming reconciliations. Smart contracts also automate workflows, reduce paperwork, and speed up transaction times.

Better traceability

Blockchain creates a transparent, time-stamped audit trail of every transaction. This is especially valuable in industries like supply chain or manufacturing, where it’s important to track product origins or transaction histories. Being able to trace data back to its source in real time can also help reveal inefficiencies and verify compliance with sustainability or regulatory standards.

Automated transactions

Smart contracts improve automation by triggering transactions or workflows once predefined conditions are met, without the need for manual intervention. This reduces delays, minimizes errors, and enhances operational efficiency across an organization.

Enhanced trust

Blockchain can be used to create a secure, permissioned network where only authorized participants can view or contribute data. This fosters greater trust, especially in industries where data integrity is crucial.

The difference between blockchain and Bitcoin

Many people take blockchain and Bitcoin to mean the same thing, but they are different:

• Blockchain is a decentralized, distributed ledger technology that records and verifies transactions across a network of computers.
• Bitcoin was the first cryptocurrency to be built on blockchain technology. It allows people to make financial transactions online without the need for intermediaries like banks. Every Bitcoin transaction is recorded on the Bitcoin blockchain, which is a public ledger maintained by a decentralized network of participants.

In short, blockchain is the technology and Bitcoin is just one application of that technology. There are many other applications of blockchain technology outside of Bitcoin, some of which we’ve illustrated throughout this article.