Ethereum is a smart-contract enabled Layer 1 blockchain. It is the base layer for many Layer 2 scaling solutions, such as Polygon, Arbitrum and Immutable X. Ethereum’s execution layer, previously known as ETH 1.0, uses proof-of-work to validate transactions, which contributes to its scalability issues. While Ethereum is the largest smart contract blockchain by market capitalisation, friction points for users include slow transaction speed (about 15 transactions per second) and high gas fees, which Ethereum’s consensus layer aims to resolve by shifting to a proof-of-stake mechanism.