Thermal ablation, which induces irreversible cellular injury from focal high-temperature tissue heating that is generated from a focal energy source, has become an accepted treatment option for focal primary and secondary malignancies in a wide range of organs including the liver, lung, kidney, bone, and adrenal glands. Given the rising complexity of treatment types and paradigms in oncology, and the wider application of thermal ablation techniques and adjuvant therapy reviewed in this article, a thorough understanding of the basic principles and recent advances in thermal ablation is a necessary prerequisite for their effective clinical use.