A range of magnetic resonance (MR) parameters are introduced, which can give rise to image contrast by using suitable pulse sequences, and that can be measured quantitatively. Their relationship to tissue pathology is given as far as possible. Techniques for their measurement, and results from multiple sclerosis, stroke, and epilepsy are given. The parameters are proton density, T1, T2, transverse magnetisation decay, which gives estimates of extracellular water and myelin concentrations, magnetisation transfer ratio and T1sat, and diffusion (including trace and anisotropy measured from the tensor matrix).