A blockchain is a continuously expandable list of data records, called blocks, which are linked together using cryptographic methods. Each block typically contains a cryptographically secure hash (scatter value) of the previous block, a time stamp and transaction data.
It is crucial that later transactions build on previous transactions and confirm these as correct by proving knowledge of the previous transactions. This makes it impossible to manipulate or redeem the existence or content of previous transactions without also destroying all later transactions.
A blockchain is used for example for:
- electoral systems
- financial transactions
- digital certificates
- messaging services
- logistics and supply chain services
- verification processes
- risk analysis