Blockchain

A blockchain is a decentralized digital ledger that records transactions across a distributed network in secure, immutable blocks linked chronologically.

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Understanding What is a Blockchain?What is a Blockchain?Think of blockchain as a public notebook that everyone owns a copy of. Whatever gets written in it is permanent and visible to all.Keep learning: a beginner’s guide

Think of blockchain as a digital ledger, a special kind of notebook that records transactions. The difference is that instead of being kept by one person or institution, copies of this notebook are stored across thousands of computers worldwide. Each computer is then called a node.

Every time something is added, like a new payment, all copies update together. This makes the system extremely difficult to tamper with.

Note: We say "blockchain" when referring to the technology in general. We can say "a blockchain" when referring to one example of blockchain technology in particular, such as the Bitcoin Network. 

 

A Simple Analogy

Imagine you and your friends keep a shared diary. Every time someone spends or receives money, you all write it down. For the diary to be valid, everyone must agree on what’s written. This way, no one can cheat or secretly erase their debt.

That’s essentially how blockchain works, except the diary is digital, and the “friends” are computers.

 

Key Features

    1. Decentralized - No single company or government controls it. The network runs collectively.
    2. Transparent - Anyone can view the records. Nothing is hidden.
    3. Secure - Once a record is written, it cannot be erased or altered.
    4. Efficient - It can move value or information without middlemen like banks.

Note: There are different ways to access or search a blockchain. One of them is to use a blockchain explorer.

 

Real-World Examples

    • Cryptocurrency Payments: Bitcoin uses blockchain to transfer money directly between people, no bank required.

    • Smart Contracts: Programs that automatically execute agreements, like paying rent instantly once both sides agree.

    • Supply Chains: Companies can track products from factory to store, ensuring authenticity and reducing fraud.

    • Voting Systems: Digital ballots can be securely recorded, making elections more transparent. DAOs are based on this principle.

Recap

Blockchain is a shared digital ledger stored across many computers that records transactions in a secure, transparent, and tamper-resistant way.

By removing central control, it enables trust, verification, and value transfer without relying on intermediaries.

Tag System

The tags found in our glossary are there to help you better understand presented definitions. They showcase how certain concepts integrate and interact within the ecosystem.

Rectangular tags signal a concept related to What is a Blockchain?What is a Blockchain?Think of blockchain as a public notebook that everyone owns a copy of. Whatever gets written in it is permanent and visible to all.Keep learning as a technology. Whereas rounded tags represent What is Cryptocurrency?What is Cryptocurrency?Cryptocurrency, often called “crypto,” is a form of digital currency that uses cryptography (advanced math and code) to keep it secure.Keep learning in more of a financial aspect. You’ll also see rectangular dashed tags for What is Web3?What is Web3?Web3 is the idea of a decentralized internet powered by blockchain.Keep learning and  rounded dashed tags for What is DeFi?What is DeFi?DeFi stands for Decentralized Finance. It refers to a collection of applications and platforms built on blockchain that allow people to transact without banks.Keep learning specifically.

Learn more about the relationship between all the tags and their respective concept with our Interactive Mind Map.

FAQ

Independent participants (nodes) maintain it by running the software and following shared rules.

They use consensus mechanisms, such as proof-of-work or proof-of-stake, to validate transactions and blocks.

Most public blockchains are transparent, but some blockchains are private or permissioned, limiting who can view data.

Generally no. Blockchains are designed to be append-only, meaning data can be added but not deleted.

Because altering past records would require controlling a majority of the network, which is extremely costly and difficult.

Not entirely. Blockchain is best suited for situations where trust, transparency, and decentralization are more important than speed or simplicity.

It can be slower, more resource-intensive, and harder to change than traditional systems.

No. While crypto was the first major use case, blockchains are also used for contracts, tracking, identity, and governance systems.

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