A blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography.
The blockchain is an incorruptible digital ledger of economic transactions that can be programmed to record not just financial transactions but virtually everything of value.
Each block typically contains a cryptographic hash of the previous block, a timestamp and transaction data.
It is an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way.
Blockchains are secure by design and exemplify a distributed computing system with high Byzantine fault tolerance.
Decentralized consensus has therefore been achieved with a blockchain.This makes blockchains potentially suitable for the recording of events, medical records, and other records management activities, such as identity management, transaction processing, documenting provenance, food traceability or voting.
A blockchain is a decentralized, distributed and public digital ledger that is used to record transactions across many computers so that the record cannot be altered retroactively without the alteration of all subsequent blocks and the collusion of the network.
This allows the participants to verify and audit transactions inexpensively. A blockchain database is managed autonomously using a peer-to-peer network and a distributed timestamping server.
A Distributed Database
Information held on a blockchain exists as a shared — and continually reconciled — database.
This is a way of using the network that has obvious benefits. The blockchain database isn’t stored in any single location, meaning the records it keeps are truly public and easily verifiable.
No centralized version of this information exists for a hacker to corrupt. Hosted by millions of computers simultaneously, its data is accessible to anyone on the internet.
Blockchain Durability and robustness
Blockchain technology is like the internet in that it has a built-in robustness. By storing blocks of information that are identical across its network, the blockchain cannot:
1. Be controlled by any single entity.
2. Has no single point of failure.
Transparent and incorruptible
The blockchain network lives in a state of consensus, one that automatically checks in with itself every ten minutes.
A kind of self-auditing ecosystem of a digital value, the network reconciles every transaction that happens in ten-minute intervals. Each group of these transactions is referred to as a “block”. Two important properties result from this:
1. Transparency data is embedded within the network as a whole, by definition it is public.
2. It cannot be corrupted altering any unit of information on the blockchain would mean using a huge amount of computing power to override the entire network.