Linac Coherent Light Source: The first five years

In the five years since achieving first light at the Linac Coherent Light Source, transformative studies have been conducted in a new regime with femtosecond pulses of short wavelength, high intensity x rays. This article summarizes these results in atomic, molecular and optical physics; condensed matter physics; matter in extreme density, temperature and pressure conditions; chemistry and soft matter; and biological structure and dynamics. In each of these areas, perspectives for future research are discussed.