The HYDRUS software package has evolved significantly since its initial development, becoming a widely used tool for simulating water, heat, and solute movement in variably saturated porous media. The latest version, HYDRUS 5, integrates the capabilities of HYDRUS-1D and HYDRUS (2D/3D) into a single platform, offering enhanced functionality for modeling subsurface processes. The software includes a range of standard and nonstandard add-on modules that expand its capabilities, such as HPx for geochemical modeling, UNSATCHEM for simulating major ion transport, Wetland for modeling wetland processes, Furrow for irrigation and fertigation, PFAS for simulating the fate of per- and polyfluoroalkyl substances, Particle Tracking for analyzing water movement, and COSMIC for integrating cosmic-ray neutron probe data. These modules allow for the simulation of complex processes, including reactive transport, multi-cropping systems, and hydraulic redistribution within the rootzone. The software also supports various boundary conditions and numerical methods, enabling the analysis of a wide range of environmental and agricultural applications. Recent developments include improved capabilities for simulating environmental isotopes, and the integration of global optimization algorithms for inverse problems. The HYDRUS software is widely used in both research and education, with numerous applications in irrigation, low-impact development, and managed aquifer recharge. The software continues to evolve, incorporating new features and improving existing ones to better address the challenges of subsurface modeling.The HYDRUS software package has evolved significantly since its initial development, becoming a widely used tool for simulating water, heat, and solute movement in variably saturated porous media. The latest version, HYDRUS 5, integrates the capabilities of HYDRUS-1D and HYDRUS (2D/3D) into a single platform, offering enhanced functionality for modeling subsurface processes. The software includes a range of standard and nonstandard add-on modules that expand its capabilities, such as HPx for geochemical modeling, UNSATCHEM for simulating major ion transport, Wetland for modeling wetland processes, Furrow for irrigation and fertigation, PFAS for simulating the fate of per- and polyfluoroalkyl substances, Particle Tracking for analyzing water movement, and COSMIC for integrating cosmic-ray neutron probe data. These modules allow for the simulation of complex processes, including reactive transport, multi-cropping systems, and hydraulic redistribution within the rootzone. The software also supports various boundary conditions and numerical methods, enabling the analysis of a wide range of environmental and agricultural applications. Recent developments include improved capabilities for simulating environmental isotopes, and the integration of global optimization algorithms for inverse problems. The HYDRUS software is widely used in both research and education, with numerous applications in irrigation, low-impact development, and managed aquifer recharge. The software continues to evolve, incorporating new features and improving existing ones to better address the challenges of subsurface modeling.