Magnetic resonance imaging (MRI) is one of the primary medical imaging modalities and a key component of the standard of care in modern healthcare systems. One of the factors that distinguishes MRI from other imaging methods is the ability to program the MRI system to reveal a wide range of imaging contrasts, where each type of contrast offers unique information about the biological sample of interest. This ability stems from the fact that both the amplitude and phase of the magnetization of the underlying tissue can be manipulated to highlight different biological phenomenon. The flexibility and capabilities offered by modern MRI systems have enabled the development of a myriad of techniques for characterizing anatomy, physiology, and function. These include methods to characterize gross anatomy, tissue microstructure, bulk blood flow, tissue perfusion, and functional changes in blood oxygenation. This article is categorized under: Laboratory Methods and Technologies > Imaging Translational, Genomic, and Systems Medicine > Diagnostic Methods.