A Public Blockchain is a network that is globally accessible by anyone anywhere in the world.
Another name for a public blockchain is a permissionless blockchain.
Participants of a public blockchain can add blocks, and initiate and execute transactions.
Bitcoin and Ethereum are the most popular decentralized public blockchains in the world.
Public blockchains are normally anonymous, where the identity of their users are unknown.
Anonymity is one of the advantages of a public blockchain. It’s what draws users in.
Public blockchains are also transparent in the fact they are primarily created using open-source software and code that can be reviewed by anyone at any time.
Public blockchain transactions, due to the transparent nature of these blockchains, can also be verified easily.
Finally, public blockchain transactions are recorded to a distributed ledger, where transactions on the blockchain are immutable – they can’t be altered or removed, only added.
Verification of these transactions doesn’t only happen on one node within the network but across a majority of the nodes, with who they share the confirmation across the entire network.
Public blockchains like Bitcoin do consume a lot of power, due to the Proof-of-Work (PoW) consensus mechanism.
Confirmation of transactions is highly energy intensive and it takes a long time to complete.
Public blockchains also have to deal with scalability issues, where more users utilizing the blockchain cause network congestion slowing down the network as a whole.