Acoustic waves are vibrations that travel through a medium, such as air, water, or solids. These waves are created by the movement of particles in the medium, which compress and expand to transmit sound. The speed of acoustic waves depends on the medium; for example, they travel faster in water than in air. Electromagnetic waves, on the other hand, do not require a medium and can travel through a vacuum. They are generated by the movement of charged particles and include a range of wavelengths, from radio waves to gamma rays. These waves carry energy and information, making them essential for technologies like radio, television, and cell phones.