Warm dark matter (WDM) is a modification of cold dark matter (CDM) where dark matter particles have initial velocities due to thermal relics or non-equilibrium decay. A high-resolution N-body simulation of WDM shows distinct observational signatures compared to CDM. WDM halos have lower concentrations and core densities, larger core radii, and fewer low-mass satellites. Small halos are formed via 'top-down' fragmentation in the cosmic web, with few forming outside it. WDM better matches observations of dwarf galaxy numbers, distribution, and formation times compared to CDM. WDM suppresses small-scale structure, leading to fewer low-mass halos and a different clustering pattern. Simulations show WDM halos form later and have lower densities. The phase space constraint limits WDM particle masses to above 400 eV. Simulations with WDM masses of 175 eV and 350 eV show reduced small-scale structure and fewer satellites. The clustering pattern in WDM differs from CDM, with small halos forming within the cosmic web. WDM models with higher masses suppress small-scale structure more effectively. The halo mass function in WDM shows a strong suppression of low-mass halos and a steeper mass function at the lowest masses. WDM halos form via pancake fragmentation at lower redshifts. The results suggest WDM could resolve CDM's small-scale problems while maintaining large-scale agreement.Warm dark matter (WDM) is a modification of cold dark matter (CDM) where dark matter particles have initial velocities due to thermal relics or non-equilibrium decay. A high-resolution N-body simulation of WDM shows distinct observational signatures compared to CDM. WDM halos have lower concentrations and core densities, larger core radii, and fewer low-mass satellites. Small halos are formed via 'top-down' fragmentation in the cosmic web, with few forming outside it. WDM better matches observations of dwarf galaxy numbers, distribution, and formation times compared to CDM. WDM suppresses small-scale structure, leading to fewer low-mass halos and a different clustering pattern. Simulations show WDM halos form later and have lower densities. The phase space constraint limits WDM particle masses to above 400 eV. Simulations with WDM masses of 175 eV and 350 eV show reduced small-scale structure and fewer satellites. The clustering pattern in WDM differs from CDM, with small halos forming within the cosmic web. WDM models with higher masses suppress small-scale structure more effectively. The halo mass function in WDM shows a strong suppression of low-mass halos and a steeper mass function at the lowest masses. WDM halos form via pancake fragmentation at lower redshifts. The results suggest WDM could resolve CDM's small-scale problems while maintaining large-scale agreement.