Ethereum added a virtual machine to the ledger. Anyone can deploy a program that runs exactly as written whenever it is called, which turned the chain from a payment rail into a platform, and ether is the asset used to pay for that computation.
The network moved from mining to proof of stake in 2022, cutting its energy use by more than ninety-nine per cent. Validators now post ether as collateral, earn a yield for honest validation and lose it for misbehaviour.
Most activity has migrated to layer-two rollups such as Arbitrum, Optimism and Base, which batch transactions off-chain and settle the result on Ethereum. Fees there are a fraction of mainnet, at the cost of extra trust assumptions that vary by rollup.