What is blockchain ledger?
While many crypto-technologies, such as Bitcoin, are permissionless, much of the legacy infrastructure is permissioned. Ongoing discussion regarding integration of distributed ledgers into legacy systems has brought attention to a growing divide:
Permissionless Ledgers (Public Blockchains) vs. Permissioned Ledgers (Private Blockchains)
Permissionless LedgersAlso called unpermissioned ledgers, allow anyone to contribute data to the ledger with all participants possessing an identical copy of the ledger. Since there is no single owner of the ledger, this methodology is more suitable for censorship resistant applications (e.g. Bitcoin).
Permissioned LedgersSometimes called private blockchains, allow for distributed identical copies of a ledger, but only to a limited amount of trusted participants only. As the network may have an owner(s), this methodology is better suited for applications requiring simplicty, speed, and greater transparency.