What is Casper (Ethereum)?

Casper is the Ethereum consensus mechanism that will transform the Ethereum network — based on a Proof-of-Work (PoW) consensus mechanism, and known as Ethereum Execution Layer (previously Ethereum 1.0) — into a Proof-of-Stake (PoS) system called Ethereum Consensus Layer (previously Ethereum 2.0). Casper is being rolled out as part of Ethereum's Beacon Chain and will consist of several upgrades. As of March 2021, Casper has been co-developed with two main implementations for Ethereum, Casper CBC (Correct by Construction) and Casper FFG (Friendly Finality Gadget).