The paper investigates the mass profiles of Λ CDM halos using high-resolution simulations spanning five decades in halo mass, from dwarf galaxies to galaxy clusters. The simulations reveal that the density profiles of Λ CDM halos are not well described by power laws but instead exhibit a logarithmic slope that decreases monotonically towards the center, becoming shallower than isothermal near the center and steeper near the virial radius. The NFW profile provides a reasonable approximation to the density and circular velocity profiles of individual halos, though systematic deviations are observed, particularly in the inner regions. These deviations suggest a steeper inner slope than previously thought, but the authors argue that the density profiles do not converge to a well-defined asymptotic inner power law. Instead, they propose a new fitting formula that better reproduces the radial dependence of the slope and minimizes errors when extrapolating results inward. The results indicate that the central density cusp is not as steep as previously thought, with no evidence for a well-defined central power-law. The density profiles of halos of different masses show a universal shape when scaled to the characteristic radius, r₋₂, and the central slope varies with mass. The paper concludes that the density profiles of Λ CDM halos are universal in shape, and that the NFW and M99 profiles describe the density and circular velocity profiles of simulated halos reasonably well. However, the best fits to the circular velocity profiles deviate by less than 10% over the region well resolved numerically, and the deviations increase inward, suggesting caution in extrapolating to smaller radii. The paper also discusses the scaling parameters of halos and their dependence on mass, showing that the characteristic density and radius vary with mass and cosmological parameters. The results suggest that the inner slopes of Λ CDM halos are not as steep as previously thought, and that the central density cusp is not as steep as the NFW profile suggests. The paper concludes that the density profiles of Λ CDM halos are universal in shape, and that the NFW and M99 profiles describe the density and circular velocity profiles of simulated halos reasonably well. However, the best fits to the circular velocity profiles deviate by less than 10% over the region well resolved numerically, and the deviations increase inward, suggesting caution in extrapolating to smaller radii.The paper investigates the mass profiles of Λ CDM halos using high-resolution simulations spanning five decades in halo mass, from dwarf galaxies to galaxy clusters. The simulations reveal that the density profiles of Λ CDM halos are not well described by power laws but instead exhibit a logarithmic slope that decreases monotonically towards the center, becoming shallower than isothermal near the center and steeper near the virial radius. The NFW profile provides a reasonable approximation to the density and circular velocity profiles of individual halos, though systematic deviations are observed, particularly in the inner regions. These deviations suggest a steeper inner slope than previously thought, but the authors argue that the density profiles do not converge to a well-defined asymptotic inner power law. Instead, they propose a new fitting formula that better reproduces the radial dependence of the slope and minimizes errors when extrapolating results inward. The results indicate that the central density cusp is not as steep as previously thought, with no evidence for a well-defined central power-law. The density profiles of halos of different masses show a universal shape when scaled to the characteristic radius, r₋₂, and the central slope varies with mass. The paper concludes that the density profiles of Λ CDM halos are universal in shape, and that the NFW and M99 profiles describe the density and circular velocity profiles of simulated halos reasonably well. However, the best fits to the circular velocity profiles deviate by less than 10% over the region well resolved numerically, and the deviations increase inward, suggesting caution in extrapolating to smaller radii. The paper also discusses the scaling parameters of halos and their dependence on mass, showing that the characteristic density and radius vary with mass and cosmological parameters. The results suggest that the inner slopes of Λ CDM halos are not as steep as previously thought, and that the central density cusp is not as steep as the NFW profile suggests. The paper concludes that the density profiles of Λ CDM halos are universal in shape, and that the NFW and M99 profiles describe the density and circular velocity profiles of simulated halos reasonably well. However, the best fits to the circular velocity profiles deviate by less than 10% over the region well resolved numerically, and the deviations increase inward, suggesting caution in extrapolating to smaller radii.