This book discusses the applied theories of wave propagation in a comprehensive manner. A wave is one of the most fundamental physics phenomena discovered by humans since ancient times. The wave is also one of the most-studied phenomena in physics which can be well elucidated by mathematics. Such studies can be the best explanation of the "science" of wave propagation, summarizing the laws of nature by employing human defined symbols, languages and operators. An in-depth understanding of waves and wave propagation can assist us in enhancement of the quality of life and guide us into a direction for future explorations of the universe and nature. The book elucidates appealing theories and applications for readers interested in studying about waves and wave propagations. It also acts as a reference for experts working in the fields described in this book.