"A blockchain is a distributed ledger with growing lists of records (blocks) that are securely linked together via cryptographic hashes."
The study of how blockchain technology can be used to create secure and transparent transactions between parties.
Cryptography: The study of secure communication techniques to prevent unauthorized access and ensure confidentiality, integrity and authenticity of data.
Distributed Systems: The architecture of systems where multiple nodes work together and share resources such as processing power, memory and storage.
Consensus Mechanisms: The process by which multiple parties agree on the state of the blockchain and validate transactions.
Smart Contracts: Self-executing digital contracts that use blockchain technology to enforce their terms and conditions.
Blockchain Platforms: Infrastructure that allows developers to create and deploy decentralized applications (dApps) and smart contracts.
Public vs Private Blockchains: The difference between a blockchain that is open to anyone and one that requires permission to join.
Decentralized Autonomous Organizations (DAOs): Organizations run on the blockchain by members who vote on decisions through smart contracts.
Digital Identity: Using the blockchain to store and verify identity information in a secure and decentralized manner.
Cryptocurrency: Digital or virtual currency that uses cryptography for security and operates independently of a central bank.
Tokenization: The process of converting real-world assets, such as property or artwork, into digital tokens on the blockchain.
Scalability: The challenge of making blockchains fast, secure and efficient enough to handle large numbers of transactions.
Interoperability: The ability of different blockchains to communicate and exchange data with each other.
Regulation: The legal and regulatory framework around blockchain and crypto assets, which differs from country to country.
Privacy and Security: Ensuring that data on the blockchain remains secure and private while still being transparent and publicly accessible.
Governance: The mechanisms and structures that determine how decisions are made and rules are enforced in a blockchain ecosystem.
Public Blockchain: This type of blockchain is open to anyone to participate and view the contents. Participants can create, verify, and add new blocks to the public chain. Transactions are transparent, and the network functions on a peer-to-peer basis.
Private Blockchain: As the name suggests, private blockchains are restricted in access and use. They are primarily used for enterprise purposes and are subject to certain permissions, controls, and conditions. They are secure, private, and allow for faster processing of transactions.
Hybrid Blockchain: This type of blockchain combines elements of both public and private blockchains. It uses the public blockchain for transparency, while the private blockchain maintains privacy, security, and speed.
Permissionless Blockchain: Permissionless blockchain allows anyone to transact on it, and it doesn't require to ask for permission from anyone to take part in the network.
Permissioned Blockchain: Permissioned blockchains require specific permissions to join the network, sustain consensus, and keep a copy of the ledger, and to validate new transactions. The most famous example is the Hyperledger Fabric.
Consortium Blockchain: Consortium blockchains are controlled by a group of organizations instead of only one, where the participation of each organization is based on their merits and credibility within the consortium. The data is shared and access is made possible for each member organization.
Federated Blockchain: This type of blockchain is almost like a hybrid between public and private blockchains. The federated blockchain consists of several organizations but is more centralized than the public blockchain, as decisions are taken by the central authority.
Sidechains: Sidechains are an additional blockchain that runs parallel to the primary blockchain. It allows for efficient transactions and faster processing, without risking the security and integrity of the primary blockchain.
Blockchain as a Service (BaaS): BaaS is a cloud-based service model that allows customers to use blockchain applications and features without having to build and maintain the blockchain infrastructure themselves.
Proof of Work (PoW): PoW is a consensus algorithm that requires significant computational power to solve complex mathematical algorithms to validate transactions and create new blocks.
Proof of Stake (PoS): PoS is another consensus algorithm that requires the user to hold a large amount of cryptocurrency to validate transactions and create new blocks.
Delegated Proof of Stake (DPoS): DPoS is a consensus algorithm that prioritizes the voting power of stakeholders to validate transactions and create new blocks.
Directed Acyclic Graph (DAG): DAG is a non-linear graph that enables a distributed ledger to scale horizontally by removing blocks altogether, noted by distributed nodes, to secure the network and confirm transactions.
Hashgraph: Hashgraph uses a unique consensus algorithm that doesn't require mining and instead uses gossip about its members' transactions to achieve consensus on the order of events forming the distributed ledger.
"Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data."
"Transaction data is generally represented as a Merkle tree, where data nodes are represented by leaves."
"Once they are recorded, the data in any given block cannot be altered retroactively without altering all subsequent blocks."
"Blockchains are typically managed by a peer-to-peer (P2P) computer network for use as a public distributed ledger."
"Nodes collectively adhere to a consensus algorithm protocol to add and validate new transaction blocks."
"A blockchain was created by a person (or group of people) using the name (or pseudonym) Satoshi Nakamoto in 2008."
"The bitcoin design has inspired other applications and blockchains that are readable by the public and are widely used by cryptocurrencies."
"The implementation of the blockchain within bitcoin made it the first digital currency to solve the double-spending problem without the need of a trusted authority or central server."
"Private blockchains have been proposed for business use."
"Others have argued that permissioned blockchains, if carefully designed, may be more decentralized and therefore more secure in practice than permissionless ones."
"Each block contains...a timestamp..."
"Based on previous work by Stuart Haber, W. Scott Stornetta, and Dave Bayer."
"Nodes collectively adhere to a consensus algorithm protocol to add and validate new transaction blocks."
"Although blockchain records are not unalterable, since blockchain forks are possible..."
"Blockchains may be considered secure by design and exemplify a distributed computing system with high Byzantine fault tolerance."
"Consequently, blockchain transactions are irreversible in that, once they are recorded, the data in any given block cannot be altered retroactively without altering all subsequent blocks."
"The bitcoin design has inspired other applications and blockchains that are readable by the public and are widely used by cryptocurrencies."
"Private blockchains have been proposed for business use."
"Computerworld called the marketing of such privatized blockchains without a proper security model 'snake oil'."