Extragalactic radio continuum surveys and the transformation of radio astronomy

Next-generation radio surveys are about to transform radio astronomy by discovering and studying tens of millions of previously unknown radio sources. These surveys will provide fresh insights for understanding the evolution of galaxies, measuring the evolution of the cosmic star-formation rate, and rivalling traditional techniques in the measurement of fundamental cosmological parameters. By observing a new volume of observational parameter space, they are also likely to discover unexpected phenomena. This Review traces the evolution of extragalactic radio continuum surveys from the earliest days of radio astronomy to the present, and identifies the challenges that must be overcome to achieve this transformational change.Radio astronomy will be transformed by future surveys that will study tens of millions of radio sources, providing new insights into a broad range of open questions in astronomy. This transformation, and the lead-up to it, is summarized in this Review.