Book excerpt: This tutorial serves as a practical guide on seismic tomography for an audience familiar with basic seismology concepts and calculus. The intent is to provide the reader with a fundamental understanding of both seismic-ray tomography and seismic-diffraction tomography. Case studies illustrate processing methodology, basic interpretation techniques, and pitfalls. This presentation assists the reader in gaining a greater understanding of and appreciation for seismic-tomography articles found in the literature.