Glossary/Spread
Spread
The bid-ask spread is best ask minus best bid. It is a quick measure of transaction cost for crossing the book at the touch. Wide spreads often indicate thin liquidity, uncertainty, or a one-sided market.
How AymarData records it
Book responses include a spread field when both sides are present. For Polymarket outcome tokens, spread is in probability points; for crypto pairs it is in quote-currency price units. Always inspect size at the touch — a tight spread with tiny size is not deep liquidity.