Vitalik initially proposed the sharding idea for scaling Ethereum blockchain. His proposal was to chop the blockchain into hundreds or thousands of independent pieces: shards. All shards share the same consensus algorithm and security model. These shards will not handle different types of task and do not need to be validated by all full nodes. Instead, each shard serves a single purpose and therefore is very efficient at it. In summary, sharding splits up the state of the network into multiple shards, where each shard has its own transaction history and a portion of the network's state. To implement the sharding idea on the blockchain, a Validator Management Contract is needed, which is a smart contract. It verifies each shard's block headers, maintains validators' stakes, and selects validators between shards pseudo-randomly. Sharding provides an alternative way to increase Ethereum's performance dramatically and could be implemented as early as 2020.