The bid-ask spread is the difference between the lowest asking price and the highest bidding price for an asset. The "bid" refers to the purchase price, whereas the "ask" refers to the selling price. There are no fixed asset prices when trading assets such as equities or cryptocurrency. Instead, prices change according to a variety of market conditions. As a result, bid and ask prices are volatile. Bid-ask spreads indicate the liquidity of an asset. A narrower spread between bid and ask prices often indicates high asset liquidity and high trading activity. A bigger disparity indicates the inverse.