What is Blockchain?
Imagine a digital record-keeping method that everyone can see but no one can secretly change. New information is added as "blocks" of data and linked together one after another. Each new block is permanently connected to the one before it. These links act as a point of verification—if a new data block comes in and its connection to the past doesn't match up, then this attempt to tamper with a past record would be instantly visible to the entire network.
This data structure—a tamper-proof chain of blocks—provides the foundation with immutability and cryptographic security. When combined with Proof-of-Work (PoW) consensus logic, it creates a truly decentralized system that solves the problem of trust by removing the need for a central authority.
The person you see on the right is Vitalik Buterin, the brain behind Ethereum.
He's explaining what blockchain is in under one minute in the clearest way possible using the technical terms.
Watch it and come back.
Where did the idea come from?
Blockchain concept originated from the need to create a secure, tamper-proof system for timestamping digital documents.
In 1991, cryptographers Stuart Haber and W. Scott Stornetta wanted to solve a fundamental problem of the digital age: how do you prove that a digital document existed at a specific point in time and hasn't been altered since? Unlike a physical document that can be notarized, a digital file can be easily changed without leaving a trace.
The Original Solution
Haber and Stornetta devised a system using a cryptographically secured chain of blocks. Their process worked as follows:
- Hashing: They would take a digital document and create a unique "fingerprint" of it called a hash. A hash is a fixed-length string of characters generated by an algorithm. Even a tiny change to the original document would produce a completely different hash.
- Timestamping: They would then collect these hashes and group them into a "block." This block was given a timestamp and a cryptographic link to the previous block in the chain.
- The Chain: By linking each new block to the one before it, they created a chronological chain. Any attempt to alter a document would change its hash, which would then break the cryptographic link to the next block, making the tampering immediately obvious. This created a permanent, immutable record of when a document existed.
This initial concept, however, still relied on a central authority to manage the chain. The true innovation came in 2008 when the pseudonymous Satoshi Nakamoto introduced the first decentralized blockchain as the public ledger for Bitcoin.
Below you will find a visual demo, which was one of the content I came across that helped me and inspired Cryptordinary (as you will see on the #BrainDump pages). It is visual introduction to the concepts behind a blockchain, the creator introduce the idea of an immutable ledger using an interactive web demo. They will mention other terms too, but dont worry much about them for now, just make sure you have some ear familiarity.