Not your grandparents' binary stars

Close binaries are the origin of many extraordinary events in the Universe, including type Ia supernovae and gravitational wave events. On the other extreme, wide binaries are easily disrupted by gravitational perturbations, making them a unique tool to probe the Galactic structures. In recent years, our understanding of binaries has been revolutionized by modern photometric, spectroscopic, and astrometric surveys. In this talk, I will begin with the lifetime measurement of short-period main-sequence binaries and discuss its implications for the formation of close binaries and their merger. Then, with the metallicity dependence and the recently developed eccentricity measurements, I will demonstrate the clear distinction between close binaries and wide binaries, which is often arbitrary in the literature. In the end, I will discuss the unsolved puzzles about the formation of twin binaries and the interplay between close and wide binaries.