Liquidity pool
A shared pot of tokens in a smart contract. A decentralized exchange swaps coins from it, and people who put tokens in earn a share of the fees. A formula sets the price inside the pool. There is no order book.
Example
You put ETH and a stablecoin of equal value into a pool. Other people swap tokens, and the fee is split among depositors.
What not to do
Do not enter a pool for a nice percentage without understanding the risk. Token prices can drift apart, and your share may end up worth less than if you had simply held the coins. Code bugs are a risk too.
WEEX