What liquidity means
Liquidity describes how easily an asset can be converted to or from cash without moving its price much. A highly liquid market has many active buyers and sellers, so orders can usually be filled quickly and close to the last traded price. A thin, illiquid market can see larger price swings from smaller orders.
How liquidity shows up
Signs often associated with liquidity include a narrow gap between the highest bid and lowest ask, steady trading volume, and depth in the order book. Major assets during active hours tend to be more liquid, while smaller or less-traded instruments, or off-peak hours, tend to be less liquid.
Why it matters
Liquidity affects how smoothly a market functions and how much prices can move when large orders arrive. In less liquid conditions, the difference between an expected and an actual fill price can widen. Liquidity is a descriptive property of market conditions and can change over time and across venues.