The Altair hard fork, the first mainnet upgrade to the Ethereum (ETH)’s beacon chain, is slated to go into effect on October 27.
The update is considered a “low stakes warm-up” to the upcoming Merge, when the current Ethereum mainnet, which is secured by a proof-of-work (PoW) consensus mechanism,  “merges” with the beacon chain proof-of-stake (PoS) system….
Read More: Ethereum Gets Its Altair Upgrade In Two Days