What is Ethereum?
Ethereum is a global, open-source platform for decentralized applications. On Ethereum, you can write code that controls digital value, runs exactly as programmed, and is accessible anywhere in the world.
Ethereum 2.0 (Eth2)
Eth2 is a long-planned upgrade to the Ethereum network, giving it the scalability and security it needs to serve all of humanity. The first stage of Eth2, called Phase 0, is planned to launch in 2020.
Eth2 will reduce energy consumption, allow the network to process more transactions, and increase security. Technically speaking, Ethereum will become a proof-of-stake blockchain and introduce shard chains. This is a huge change to how Ethereum works and it should bring equally huge benefits.
But it’s only a change to Ethereum’s infrastructure. If you’re already an ETH holder, dapp user or dapp developer, you don’t need to do anything because Eth2 will be compatible with the main Ethereum network you use today. You’ll be able to use the ETH you own today in Eth2 too.