isl is a library for manipulating sets and relations of integer points bounded by linear constraints. Supported operations on sets include intersection, union, set difference, emptiness check, convex hull, (integer) affine hull, integer projection, computing the lexicographic minimum using parametric integer programming, coalescing and parametric vertex enumeration. It also includes an ILP solver based on generalized basis reduction, transitive closures on maps (which may encode infinite graphs), dependence analysis and bounds on piecewise step-polynomials.