Sound waves are vibrations that travel through the air, water, or solid materials. They are created when an object, like a musical instrument or a person's voice, vibrates and pushes against the surrounding medium. These vibrations create areas of high and low pressure, which move outward from the source, allowing us to hear sounds. Sound waves can be classified into two main types: longitudinal waves and transverse waves. In longitudinal waves, the particles of the medium move back and forth in the same direction as the wave, while in transverse waves, the particles move perpendicular to the direction of the wave. Most sound waves we encounter in daily life are longitudinal.