Blockchains such as Bitcoin, Ethereum and many others are open to the public. However, a private blockchain allows organizations within a particular industry to transfer funds or execute contracts that are not in the public domain. Like their public counterpart, the private blockchain provides immutable proof of ownership that cannot be altered, and it offers faster processing than the large public blockchain networks. Unlike public blockchains, which are "permissionless," private blockchains are "permissioned," because approval is required from some authority to become a user, validator or miner.
A hybrid blockchain is both permissioned (private) and permissionless (public), allowing public access to some data but not all. Thus, hybrid blockchains have both centralized and decentralized attributes. See blockchain