Liquidity in crypto is what determines how easy (and fast) you can buy or sell a token without affecting its price. If a token has high liquidity, there are many buyers and sellers, so you can trade without significant slippage. If it has low liquidity, it can be nearly impossible to sell without losing value. In DEXs like Uniswap or PancakeSwap, liquidity is provided by users through pools, and in CEXs like Binance, the platform manages the order books. Understanding liquidity is key to avoiding getting stuck with tokens that are impossible to sell.