This chapter describes the basics of magnetic resonance imaging (MRI) and functional MRI (fMRI). It is aimed at beginners in the field and does not require any previous knowledge. Complex technical issues are made plausible by presenting plots and figures, rather than mathematical equations. The part dealing with the basics of MRI covers spins, spin alignment in external magnetic fields, the magnetic resonance effect, field gradients, frequency encoding, phase encoding, slice selection, k-space, gradient echoes, and echo-planar imaging. The part dealing with fMRI covers transverse relaxation times, the basics of the blood oxygen level dependent (BOLD) contrast, and the hemodynamic response.