Chapter 4 examines magnetic resonance imaging (MRI) as a cornerstone technology for visualizing brain structure with remarkable precision. The chapter traces MRI’s development from Wolfgang Pauli’s discovery of nuclear spin properties through Nobel Prize-winning innovations by Bloch, Purcell, Lauterbur, and Mansfield that enabled spatial encoding of magnetic resonance signals. It explains the physical principles underlying MRI and how powerful magnetic fields align hydrogen atoms in tissue, followed by precisely tuned radiofrequency pulses that excite these atoms, resulting in detectable signals that vary by tissue composition. The text explores technical considerations essential for high-quality image acquisition, including magnetic field strength, head coil design, and pulse sequence parameters that determine tissue contrast in T1, T2, and FLAIR imaging. Considerable attention is given to image processing methods, distortion correction, registration, normalization, segmentation, and smoothing that prepare brain images for meaningful analysis. By assessing MRI’s comparative advantages over other structural imaging modalities, including its non-ionizing radiation profile and superior tissue differentiation, alongside practical considerations of safety protocols and experimental design, the chapter discusses MRI’s foundational role in modern neuroimaging while acknowledging the tradeoffs between spatial resolution, acquisition time, and signal quality that researchers must navigate when designing studies.