PFC2D (Particle Flow Code in 2 Dimensions) is a discontinuum code used in analysis, testing, and research in any field where the interaction of many discrete objects exhibiting large-strain and/or fracturing is required. Because PFC2D is not designed to examine a particular type of problem, its range extends to any analysis that examines the dynamic behavior of a particulate system. Highlighted Features: Dynamic motion and interaction of assemblies of arbitrarily-sized particles are modeled; Properties are associated with individual particles, allowing continuous gradations in properties and particle radii; Clump logic supports creation of groups of slaved particles that may represent general grain shapes; Any number of arbitrarily-oriented line segments or planar convex polygons may be specified as walls, each with its own contact properties