An acoustic wave is a type of mechanical wave that travels through a medium, such as air, water, or solids, by causing particles in that medium to vibrate. These vibrations create areas of compression and rarefaction, allowing sound to propagate. Acoustic waves can be classified into longitudinal waves, where particle movement is parallel to the wave direction, and transverse waves, where particle movement is perpendicular. Acoustic waves are essential in various applications, including sonar for underwater navigation, ultrasound in medical imaging, and acoustic engineering for designing soundproof spaces. Understanding these waves helps in fields like physics, engineering, and environmental science.