Is Bitcoin public or private?

Public. Anyone can run a node, view transactions, and participate without permission.

Do private blockchains still use consensus?

Yes, though typically among a small, known set of participants rather than a large open network.

Which is more secure?

Public chains derive security from broad, open participation; private chains rely on trust in the controlling organization instead.

Public vs. Private Blockchains: What's the Difference?

A public blockchain is open for anyone to join, read, and transact on; a private blockchain restricts participation to an approved set of members. The choice shapes how decentralized, transparent, and fast the network can be, building on \[pillar hyperlink: What Is Blockchain\].

Definitions

Public blockchains, like Bitcoin and Ethereum, are permissionless. Anyone can run a node or submit a transaction. Private, or permissioned, blockchains restrict who can participate, usually controlled by a company or consortium.

Permission models

Public chains rely on open participation and broad consensus among independent nodes, discussed further in What Is a Blockchain Node. Private chains grant access selectively, trading some decentralization for speed and control.

Examples

Bitcoin and Ethereum are the best-known public blockchains. A supply-chain tracking system shared among a handful of manufacturers is a typical private blockchain use case.

When each is used

Public blockchains suit situations that need censorship resistance and open verification, like holding an independent asset. Private blockchains suit organizations that want blockchain's record-keeping benefits without opening the network to the public.

Definitions

Permission models

Examples

When each is used

Frequently asked questions