Many of the terpenes compounds are naturally occurring organic products abundant in plants, which have been employed for centuries as odorants because of their aromatic qualities. In the last decades, their valuable properties have attracted growing interest in the pharmaceutical area. In fact, a large number of the world’s population uses plant extracts or their active compounds for health related purposes. Due to the continuous research efforts on terpenes compounds, numerous advances have been made in many aspects including advanced extraction and processing approaches, molecule structure analysis, usage for flavor enrichment, and most importantly, its potential pharmaceutical applications. This book manages to cover many of the recent developments. The potential of some monoterpenes has been reviewed for their use as substrates to obtain new natural flavor compounds with economic and commercial interest. The potential medicine functions of terpenes have been thoroughly discussed in four chapters, including: the current knowledge on the antitumor potential of diterpenes in relevant cancers; the application of rosemary extracts as cancer therapy which contain a high concentration of phenolic diterpenes; the possible development of an effective immunotherapy for cancer originated from triterpene compounds such as uncarinic acid and ursolic acid; and the promising antibacterial, antioxidant, phytotoxic, insecticidal activities of essential oils extracted from the leaves and bugs of Syzygium. After these discussions and reviews on functions, the later chapters change to other interesting topics, such as a review of the development of effective extraction methods with extraction efficiency, as well as the description of recent advances in the environmentally benign oxidative processes where greener oxidants are used. The last two chapters discuss structures of terpenes: firstly, two computational chemistry approaches are introduced which can serve as important tools in predicting molecule structures and elucidate the mechanisms of action. Finally, the structures of two recently reported pentacyclic triterpenes and their pharmacological potential are discussed.