An ERC20 token that represents the account's share of the total supply of stETH tokens. WstETH token's balance only changes on transfers, unlike StETH that is also changed when oracles report staking rewards and penalties. It's a "power user" token for DeFi protocols which don't support rebasable tokens. The contract is also a trustless wrapper that accepts stETH tokens and mints wstETH in return. Then the user unwraps, the contract burns user's wstETH and sends user locked stETH in return. The contract provides the staking shortcut: user can send ETH with regular transfer and get wstETH in return. The contract will send ETH to Lido submit method, staking it and wrapping the received stETH.
