A private blockchain is a blockchain that is owned and managed by a single entity. Unlike a public blockchain, a private blockchain has an administrator who controls who can access the network and participate in transactions. Private blockchains are also known as permissioned blockchains, as they have restrictions on who can interact with the network. The participants in a private blockchain are typically chosen by the blockchain developer or administrator. Private blockchains are used for internal purposes by organizations and are not accessible to the general public.

Characteristics:

:black_small_square:Permissioned blockchains are a type of distributed ledger where access to the network is restricted by a validator or group of validators.
:black_small_square:By nature, permissioned blockchains tend to be more efficient in database management and auditing compared to other types of networks. Not everyone can run a full node or start mining on a permissioned blockchain.
:black_small_square:In addition, not everyone can make transactions on the chain or review the blockchain using a blockchain explorer. A user has to be granted permission by a blockchain authority before he or she can access the network, making it a centralized network.
:black_small_square:However, performance is faster since fewer nodes participate. Permissioned blockchains are also attractive to users because they offer on-demand services.
Source: geeksforgeeks