Permissionless blockchains are open networks that allow anyone to participate in the consensus process without the need to obtain approval, permission, or authorization.
The key characteristics of permissionless blockchains are but not limited to:
Transparency of transactions
Anonymity
Absence of central authority
Open-source code
Some examples of permissionless blockchains include Bitcoin (BTC), Ethereum (ETH), and BNB Smart Chain (BNB). Any user with an internet connection has the ability to join the network, send and receive transactions, view and contribute to the code, operate a node, and participate in the consensus process.
Permissioned blockchains, on the other hand, are usually controlled by a centralized entity. Commonly known as private blockchains, such networks have limits on who can verify transactions and interact with the information recorded on their distributed ledgers. Private blockchains are typically used by enterprises that aim to utilize blockchain technology but want to ensure that specific information remains private, for either regulatory or competitive reasons.
Permissionless blockchains are typically more secure as the possibility of collusion by bad actors within the network is reduced. However, permissionless blockchains can be relatively slow as they face scalability issues. They can only authenticate a limited number of transactions in a given time.
In a nutshell, permissionless blockchains offer decentralization and are open to everyone, while permissioned models are more centralized and restrictive. This isn’t without sacrifice as decentralization usually comes at the cost of speed and scalability.