These graphs plot the proportion of individuals surviving without an event over the study period. Time is typically depicted on the horizontal axis, while the proportion of study participants surviving is on the vertical axis. A curve is plotted for each group in the study. Separation between the curves usually indicates differences in treatment effectiveness.
One advantage of Kaplan-Meier curves is that they are able to account for all patients in a study, even those who dropped out or were lost to follow up. They help doctors get an idea of median survival times, and they help researchers compare the effects of different treatments between groups in a study.