Preface to the special topic on active matter

<正>Active matter refers to systems composed of individual units that consume locally stored energy to generate mechanical motion. Examples of active matter include biological entities such as schools of fish, flocks of birds, bacterial colonies, and synthetic systems such as self-propelled colloidal particles and engineered nanobots. The study of active matter seeks to provide understanding for complex behaviors and emergent phenomena arising from interactions of these energy-consuming units, with implications for fields ranging from physics and biology to materials science and robotics.