Public blockchain networks
A public blockchain is one that anyone can join and participate in, such as Bitcoin. Drawbacks might include substantial computational power required, little or no privacy for transactions, and weak security. These are important considerations for enterprise use cases of blockchain.
Private blockchain networks
A private blockchain network, similar to a public blockchain network, is a decentralized peer-to-peer network, with the significant difference that one organization governs the network. That organization controls who is allowed to participate in the network, execute a consensus protocol and maintain the shared ledger. Depending on the use case, this can significantly boost trust and confidence between participants. A private blockchain can be run behind a corporate firewall and even be hosted on-premises.
Permissioned blockchain networks
Businesses who set up a private blockchain will generally set up a permission-based blockchain network. It is important to note that public blockchain networks can also be a permission. This places restrictions on who is allowed to participate in the network, and only in certain transactions. Participants need to obtain an invitation or permission to join.
Multiple organizations can share the responsibilities of maintaining a blockchain. These pre-selected organizations determine who may submit transactions or access the data. A consortium blockchain is ideal for business when all participants need to be permissioned and have a shared responsibility for the blockchain.