Race condition
A bug that depends on the timing or order of events, so it only happens sometimes.
Definition
A race condition happens when the result depends on which of two or more things finishes first, such as two network requests or a fast double tap. These bugs are often intermittent and hard to reproduce, so testers try fast, repeated and interrupted actions.
In practice
Tapping "Place order" twice very quickly creates two orders and charges the card twice.
Learn it in context
Lessons that use this term.