A very, very concise brief is it's a concurrent (happening at the same time) network upgrade from PoW (proof of work) to PoS (proof of stake). The new chain cal

A very, very concise brief is it's a concurrent (happening at the same time) network upgrade from PoW (proof of work) to PoS (proof of stake). The new chain called the beacon chain will operate alongside the "old" one until a full cut-over happens some time in the future. Predicted 1-2 years.