Price-Time Priority
Trade MechanicsBest price first, earliest first at the same price — the queue rule behind the complaint that price touched your limit and nothing filled.
Price-time priority is the rule most order books use to decide which resting order is filled first: the best price wins, and among orders at the same price the one entered earliest wins. It is why two identical limit orders at the same level can have very different outcomes — the earlier one sits ahead in the queue and may be filled by a trade that never reaches the later one.
Spot forex has no single central book, so the rule applies venue by venue rather than market wide, and a retail client dealing against a broker's own quotes is not standing in a public queue at all. It still shapes the prices those quotes are built from, and it explains a familiar frustration: price traded at your limit level and your order did not fill, because the volume that arrived was consumed by orders already in front of yours.