Spread
The gap between the highest bid and the lowest ask, a basic measure of trading cost and liquidity.
The spread is the distance between the best bid and the best ask. On a liquid Bitcoin pair it might be a single dollar on a $100,000 coin, a rounding error. On a tiny altcoin it can be 2% or more, which you pay every time you enter and exit.
A tight spread signals healthy liquidity and active competition among traders. A wide one warns of thin markets, where getting in and out is costly. Market makers earn their living off the spread, buying at the bid and selling at the ask thousands of times a day.
Related terms
The highest price a buyer is currently willing to pay for an asset on the order book.
Ask PriceThe lowest price a seller is currently willing to accept for an asset on the order book.
LiquidityHow easily an asset can be bought or sold near its current price without moving that price much.
SlippageThe difference between the price you expected on a trade and the price it actually executed at.