A blockchain is a decentralized global public ledger system that underpins - notably bitcoin - transactions.
In a blockchain, each successive block contains a cryptographic hash of the prior blocks. Nothing is ever erased. Anonymised data is accessible by all, which means audits are free, regular and incorruptible.
Blockchains make possible low-cost, instantaneous, auditable, and transparent transactions of all kinds (money, contracts, property, information...).
There are literally thousands of blockchain applications in fields such as banking, legal, research, energy, supply chain or healthcare (etc.). The development of these applications contributes to creating more efficient, transparent, and accountable services worldwide.