Private Blockchains

On a public blockchain, every transaction and change to the blockchain's state is visible to all. Anyone with internet access can see the transaction data. Block Explorers are one way to conveniently access the data on a chain. Although the identities of participants are often pseudonymous, the transaction data itself is open for anyone to see.

However, there are many instances, especially in business or enterprise settings, where such transparency isn't desirable. A company might be conducting a high-value transaction that it doesn't want competitors or others in the market to see. There might also be legal or regulatory reasons for needing to keep transaction data private.

In a private, permissioned blockchain, the visibility of transactions is limited to a select group of individuals or entities. This way, sensitive data isn't exposed. Only those who have been granted the necessary permissions can view the transaction data, and these permissions can be tightly controlled and monitored by network administrators.

Further, transactions in a private blockchain can be encrypted, adding an extra layer of security. Even within the network, details about specific transactions can be hidden from certain participants, based on their level of permission. This allows for a much higher degree of confidentiality, as specific data can be revealed only on a need-to-know basis.

In summary, privacy in the context of private, permissioned blockchains isn't just about restricting who can join. It's about having granular control over who can see what data, and when. It's about providing a secure, confidential environment where sensitive transactions can occur without the risk of exposure to unintended parties.

This has made private, permissioned blockchains an attractive option for businesses and organizations dealing with sensitive data, high-value transactions, or strict confidentiality requirements.

Private Blockchains

The data of Avalanche L1s, by default, are publicly available. This means that every node can sync and listen to ongoing transactions/blocks in these blockchains, even if they're not validating the network. Nodes may do this for indexing purposes or just having access to the current state of the blockchain without relying on third-parties.

Avalanche L1 validators can choose not to publish data from their blockchains. If a node sets validatorOnly to true, the node exchanges messages only with the blockchain's validators. Other peers won't be able to learn contents of this blockchain from their nodes.