There are four main types of decentralized or distributed blockchain networks.
Public blockchain networks
Public blockchains do not require permissions; anyone can join them. All members of such a blockchain have equal access to read, edit, and verify the blockchain. Public blockchains are primarily used to exchange and mine cryptocurrencies such as Bitcoin, Ethereum and Litecoin.
Private blockchain networks
An organization can control multiple private blockchains, also known as managed blockchains. The agency decides who can become members and what privileges they have within the network. Private blockchains are only partially decentralized because they have access restrictions. One example of a private blockchain is Ripple, a digital currency exchange network for businesses.
Hybrid blockchain networks
Hybrid blockchains combine elements of both private and public networks. Companies can build private, permission-based systems with public systems. In this way, companies can control access to specific data stored in the blockchain while keeping the rest of the data public. Companies use smart contracts to allow public members to check whether private transactions have been completed. Hybrid blockchains, for example, could grant public access to digital currencies while keeping bank-owned currencies private.
Alliance blockchain network
The Consortium blockchain network is overseen by a group of organizations. A number of pre-selected organizations share responsibility for maintaining the blockchain and determining data access rights. For industries where many organizations share common goals and can benefit from shared responsibilities, federated blockchain networks are generally preferred. The Global Shipping Business Network Consortium, for example, is a non-profit blockchain Consortium dedicated to digitizing the Shipping industry and enhancing collaboration among Shipping operators.