Acoustic waves are vibrations that travel through a medium, such as air, water, or solids. These waves are created when an object vibrates, causing nearby particles to move and transmit the energy. The speed and behavior of acoustic waves depend on the properties of the medium they travel through. There are two main types of acoustic waves: longitudinal waves and transverse waves. In longitudinal waves, particles move parallel to the direction of the wave, while in transverse waves, particles move perpendicular to the wave's direction. Acoustic waves are essential in various applications, including music, sonar, and medical imaging.