One of the advanced features implemented in the LendingPool contract is the tokenization of the lending position. When a user deposits in a specific reserve, he receives a corresponding amount of aTokens, tokens that map the liquidity deposited and accrue the interests of the deposited underlying assets. Atokens are minted upon deposit, their value increases until they are burned on redeem or liquidated. Whenever a user opens a borrow position, the tokens used as collateral are locked and cannot be transferred.