A wave is non-dispersive if its phase velocity is independent of frequency/wavelength (all frequency components travel at the same speed), while a dispersive wave has a phase velocity that depends on frequency/wavelength. Ocean surface gravity waves and capillary waves are both classically dispersive (their phase velocities depend on wavelength via the deep-water dispersion relations for gravity and surface-tension-driven waves), and Love waves are inherently dispersive because they require a velocity contrast between a surface layer and underlying half-space to exist at all; Rayleigh waves, by contrast, are non-dispersive in an idealized homogeneous, isotropic elastic half-space, traveling at a single constant velocity (about 0.92 times the shear-wave velocity) independent of frequency.