What is an order book?

The public list of standing buy and sell offers at each price. How Polymarket and Kalshi match trades.

An order book is two ladders: people offering to buy YES at 61¢, 60¢, 59¢… and people offering to sell at 62¢, 63¢, 64¢… When a ladder rung gets eaten, the price has moved. It's the market's machinery with the cover off.

Foresee replaces the ladders with an automated market maker, one pool that always quotes a price, because two taps beats reading ladders on a phone. The economics are equivalent; the furniture is smaller.