Online dating has become a widespread feature of modern social life. In less than two decades, seeking partners through commercial intermediaries went from being a marginal and stigmatised practice to a common activity. This makes online dating interesting to scientific inquiry in two ways. First, as a research topic in its own right: online dating is indicative of changing sexual norms and behaviours. Second, data from dating platforms can be used to study partner preferences and matching mechanisms and to test theories on partner choice.