wstETH is a wrapped version of stETH. Instead of rebasing, or changing account holdings daily it is similar to a c-token. It represents a pro-rata ownership of the staked ETH (stETH). When someone exits wstETH they are returned principal stETH + stETH earnings. wstETH is minted and burned as stETH is wrapped and unwrapped. Lido is a liquid staking protocol for POS blockchains. It gives you a liquid token that represents your staked collateral and earnings over time. Lido removes the need to run infrastructure and enabling continued participation in DeFi.