Viscoelastic theory is introduced, using ice as the material under consideration. Linear theory is first introduced, based on elasticity of the springs and on linear viscosity of the dashpots. The nonlinearity of the dashpots in modelling ice deformation is then introduced. The “crushed layer” and analysis by Kheisin and co-workers is outlined, based on linearly viscous modelling. Kelvin and Burgers models are introduced. Microstructural change is modelled using damage mechanics and state variables for material points. Stress and strain re-distribution arises from this aspect, as well as from nonlinearity with stress. Schaperys modified superposition principle is introduced.