This book discusses various approaches of the active research going on in the field of acoustic waves. The concept of acoustic wave is an extensive one; it materializes in a variety of mediums, from solids to plasmas, and at varying length and time scales which range from sub-micrometric layers in microdevices to seismic waves in the Sun's interior. Theoretical attempts lead to a comprehensive understanding of this phenomenon. Such waves are useful in exploring the characteristics of a variety of structures, be it inorganic layers and/or other bio-structures. These waves can also function as a tool to influence matter, from the gentle evaporation of bio-molecules to be evaluated, to the phase conversions inferred by intense shock waves. Furthermore, a whole class of widespread micro tools, inclusive of filters and sensors, depends upon the behavior of these waves propagating in fine layers. The book highlights acoustic waves as manipulative tools and as microdevices.