A warmer atmosphere has more water vapor. Scientists have been trying to predict what this means for precipitation, but this is more complex and harder to model than temperature. One explanation has been that the intensity of extreme precipitation events will increase at a rate proportional to the increase in atmospheric moisture. But recent findings show that this explanation is too simplistic. There are many ways to define extreme precipitation, and the choice of definition affects how it responds to warming. Researchers must choose their definition of extreme precipitation with care and articulate it clearly, and users should consider how extreme precipitation is defined when interpreting analyses of its change with warming.