In contrast to traditional approaches particular in protein NMR, in which the broad lines associated with protons effectively relegate this nucleus to mixing of magnetization, recent developments of hardware (very fast MAS) and reduction of dipolar interactions by deuteration have made protons as versatile as they are in solution NMR. This includes spectral dispersion in multi-dimensional experiments as well as structurally valuable restraints and parameters important for studying the materials' dynamics. Studies of solids by NMR relaxation experiments are affected by the following general observations. The experimental decay of longitudinal magnetization follows the exponential law if the spin-diffusion mechanism is completely dominant; then a single relaxation time characterizes all of the nuclei, even those that are not chemically or structurally equivalent. The spin-diffusion mechanism is typical of systems with nuclei experiencing strong dipolar interactions (protons, fluorine or phosphorus nuclei at relatively small concentrations of paramagnetic centers) under relatively slow MAS. For other nuclei with weak dipolar coupling at a high concentration of paramagnetic centers, relaxation can be non-exponential following a stretched exponential function, exp(–(τ/T1)β) or exp(–(τ/T2)β). For paramagnetic solids, the β value of 0.5 corresponds to relaxation via direct electron–nucleus dipolar interactions without spin diffusion, while intermediate values between 0.5 and 1.0 can be attributed to a diffusion-limited mechanism. Membrane proteins and amyloid fibrils, the latter related to Alzheimer's disease and Parkinson's disease, are two examples of applications where solid-state NMR spectroscopy complements solution-state NMR spectroscopy and beam diffraction methods (e.g. X-ray crystallography, electron microscopy). Solid-state NMR structure elucidation of proteins has traditionally been based on secondary chemical shifts and spatial contacts between heteronuclei. Currently, paramagnetic contact shifts and specific proton-proton distances are also used for higher resolution and longer-range distance restraints. Solid-state NMR spectroscopy serves as an analysis tool in organic and inorganic chemistry, where is used as a valuable tool to characterize chemical composition, supramolecular structure, local motions, kinetics, and thermodynamics, with the special ability to assign the observed behavior to specific sites in a molecule. Objects of ssNMR studies in materials science are inorganic/organic aggregates in crystalline and amorphous states, composite materials, heterogeneous systems including liquid or gas components, suspensions, and molecular aggregates with dimensions on the nanoscale.