Blockchain technology is the concept or protocol behind the running of the blockchain. Blockchain technology makes cryptocurrencies (digital currencies secured by cryptography) like Bitcoin work just like the internet makes email possible.
The blockchain is an immutable (unchangeable, meaning a transaction or file recorded cannot be changed) distributed digital ledger (digital record of transactions or data stored in multiple places on a computer network) with many use cases beyond cryptocurrencies.
Immutable and distributed are two fundamental blockchain properties. The immutability of the ledger means you can always trust it to be accurate. Being distributed protects the blockchain from network attacks.
Each transaction or record on the ledger is stored in a “block.” For example, blocks on the Bitcoin blockchain consist of an average of more than 500 Bitcoin transactions.
The information contained in a block is dependent on and linked to the information in a previous block and, over time, forms a chain of transactions. Hence the word blockchain.
Types of Blockchains There are four types of blockchains:
Public Blockchains Public blockchains are open, decentralized networks of computers accessible to anyone wanting to request or validate a transaction (check for accuracy). Those (miners) who validate transactions receive rewards.
Public blockchains use proof-of-work or proof-of-stake consensus mechanisms (discussed later). Two common examples of public blockchains include the Bitcoin and Ethereum (ETH) blockchains.
Private Blockchains Private blockchains are not open, they have access restrictions. People who want to join require permission from the system administrator. They are typically governed by one entity, meaning they’re centralized. For example, Hyperledger is a private, blockchain.
Hybrid Blockchains or Consortiums Consortiums are a combination of public and private blockchains and contain centralized and decentralized features. For example, Energy Web Foundation, Dragonchain, and R3.
Sidechains A sidechain is a blockchain running parallel to the main chain. It allows users to move digital assets between two different blockchains and improves scalability and efficiency. An example of a sidechain is the Liquid Network.
History of Blockchain Blockchain isn’t just a database, it’s a new technology stack with ‘digital trust’ that is revolutionizing the way we exchange value and information across the internet, by taking out the ‘gatekeepers’ from the process. For a complete and more detailed deep dive check out our article: A Concise History of Blockchain Technology
Blockchain history goes back farther than you might imagine, but we’ve condensed it by answering four critical questions:
Who Invented Blockchain? The first blockchain-like protocol was proposed by cryptographer David Chaum in 1982. Later in 1991, Stuart Haber and W. Scott Stornetta wrote about their work on Consortiums.
But it was Satoshi Nakamoto (presumed pseudonym for a person or group of people) who invented and implemented the first blockchain network after deploying the world’s first digital currency, Bitcoin.
Cryptography is a deep and fascinating discipline with a history that goes back further than blockchain. For a richer understanding of how cryptography helps blockchain technology, check out: Why Cryptography Makes Blockchain Unstoppable
Who Owns Blockchain Technology? Because blockchain technology is the technology behind the blockchain, it cannot be owned. It’s like the internet. But anyone can use the technology to run and own their own blockchains.
Who Founded Bitcoin? Satoshi Nakamoto.
Who Sent and Received the First Bitcoin Transaction? Nakamoto sent ten bitcoins to Hal Finney, who built the first reusable proof-of-work system in 2004.