NMR spectroscopy and X-ray crystallography have traditionally been viewed as rivals in three dimensional protein structure elucidation, NMR being less successfull one. The fundamental difference between NMR and X-rays lies is the following: X-rays provides almost direct spatial information about atomic positions, while NMR signal directly encodes frequency of nuclei (more precisely of nuclear spins}. After introducing basic physical principles of NMR, the standard pipeline of sample preparation and signal assignment will be explained, with emphasis on description to various useful paramaters that can be extracted without previous structure knowledge, however are very useful in characterizaation of a system under scope. Namely chemical shifts, residual dipolar couplings and paramagnetic relaxation enhancemets. A special attention will be paid to NMR methods for characterization of protein dynamics on various timescales. Specifically the possibility of characterizing the low populated conformational protein states opens a path to a challenging goal of describing protein as a dynamic ensemble of functional states. A real life examples of studies of protein-protein and protein-small molecule interactions will be described and explained.