Bitcoin is an example of a public blockchain. With a public blockchain, there is not a single authority that can alone control how the state of the blockchain evolves. The decisive feature why a public blockchain is public is because there are no restrictions on new participants. Therefore, data on public blockchains can be accessed by everyone. By issuing a digital currency, an incentive is created for each participant to behave fairly.
Examples of public blockchains include
- Bitcoin Cash
Consortium Blockchain or Federated Blockchain
Hyperledger is an example of a consortium blockchain. In contrast to a public blockchain, only pre-selected participants are accepted. Therefore, this type of blockchain is not open to everyone, but semi-private. Importantly, each participant has equal power. This can be used, for example, to set up a system for consensus-building between organizations. A consortium blockchain is usually much more performant than a public blockchain, but is also less decentralized which is why individual participants get more power.
Examples of a consortium or federated blockchain include
Multichain is an example of a private blockchain. While a consortium blockchain has several selected participants (e.g. several organizations), a private blockchain has a participant who has sole control over the rules of the blockchain. For most applications a private blockchain is not necessary and can be replaced by a decentralized database.
Examples of a private blockchain include