Abstract: Over 700,000 asteroids have been cataloged to date, of which nearly 20,000 are "near-Earth asteroids" (NEAs), and some of those pose a threat of future collision with Earth (although there is no imminent danger from asteroids being tracked currently). The Double Asteroid Redirection Test (DART), a NASA mission led by the Johns Hopkins University Applied Physics Laboratory, is a technology demonstration of using a kinetic impactor to deflect such potentially hazardous asteroids. The mission will target the tiny 150 m-diameter moon (named Dimorphos) of binary asteroid Didymos, striking it with the 560 kg DART spacecraft at around 6.6 km/s, changing the moon's 12 h orbital period around its larger companion by at least 7 minutes. The impact will have no significant bearing on any future encounter of Didymos with Earth. In this talk, I will provide background about asteroids (including binaries), the hazard they pose and possible corresponding mitigation strategies, and details about the DART mission. DART, which is on schedule to enter its launch window in July 2021 for a planned impact of Dimorphos in September 2022, is part of a broader cooperation with the European Space Agency (ESA) called the Asteroid Impact and Deflection Assessment (AIDA). As part of this cooperation, in 2024, ESA plans to launch the Hera spacecraft to survey the Didymos system.