What Is the ‘Price-Time Priority’ Rule Used by Traditional Centralized Exchanges?

The price-time priority rule is the standard mechanism CEXs use to match orders in their central order book. It dictates that the highest bid and the lowest ask are executed first (price priority).

If multiple orders share the same price, the order that was submitted earliest is executed first (time priority). This strict, transparent, and centrally enforced rule is fundamental to preventing front-running in traditional markets, as it removes any discretionary power over order execution.