Paris (PArallel, Robust, Interface Simulator) is a finite volume code for simulations of immiscible multi fluid or multiphase flows. It is based on the "one-fluid" formulation of the Navier-Stokes equations where different fluids are treated as one material with variable properties, and surface tension is added as a singular interface force. The fluid equations are solved on a regular structured staggered grid using a second-order explicit projection method. The interface separating the different fluids is tracked either using a Front-Tracking (FT) method where the interface is represented by connected marker points, or by a volume of fluid (VOF) method where the marker function is advected directly on the fixed grid. Paris is written in Fortran95/2002 and parallelized using MPI and domain decomposition. It is based on several earlier FT or VOF codes such as FTC3D, Surfer or Gerris. These codes and similar ones, as well as PARIS, have been used to simulate a wide range of multifluid and multiphase flows. PROGRAM SUMMARY Program Title: PArallel Robust Interface Simulator-Paris Licensing provisions: GPLv3. Programming language: Fortran95/2002. Parallelized using MPI and domain decomposition. Nature of problem: Paris is a free code, or software, for the computational fluid dynamics (CFD) of multiphase flows, or computational multiphase fluid dynamics (CMFD), typically simulations of interfacial fluid flow, such as droplets, bubbles or waves as described in the book by Tryggva-son, Scardovelli and Zaleski [1]. It solves the Euler or Navier-Stokes equations in the one-fluid formulation of two-phase flow, with constant surface tension. It computes complex flows such as fast atomizing jets or droplets, expanding cavitation bubble clusters and multiphase flow through porous media Solution method: The code mostly implements the methods described in the book by Tryggvason, Scardovelli and Zaleski [1]. Time stepping is performed using a simple second order in time predictor corrector method with an explicit projection for the pressure. Spatial discretisation is by finite volumes on a regular cuboid grid. Interface tracking is performed with either the Volume-Of-Fluid (VOF) or the Front-Tracking method.