Immutability, Transparency, and Trustlessness

An open permissionless database

A blockchain is an open database that is stored and updated across multiple computers in a network, known as nodes. Anyone can read and write in this database, but no one in particular controls it.

Because this database records transactions and balances that involve very large sums of money, it has to be absolutely tamper-proof. To ensure the integrity of this database, whenever it's updated, every node in the network must agree upon its current state for it to be considered valid.

Now, some nodes may try to validate a version of the blockchain that doesn't correspond to reality, for instance, because they prefer a version of the blockchain in which they get billions out of thin air or because they simply don’t have the same data as everyone else. To ensure that everyone agrees on the same version of the blockchain, the network uses a consensus mechanism.

The Ethereum network previously used a consensus mechanism known as proof-of-work, where any node that wants to validate ...