Waves can be classified into two main types: mechanical waves and electromagnetic waves. Mechanical waves require a medium, such as air, water, or solid materials, to travel through. Examples include sound waves and water waves. These waves can be further divided into transverse waves, where particles move perpendicular to the wave direction, and longitudinal waves, where particles move parallel to the wave direction. In contrast, electromagnetic waves do not need a medium and can travel through a vacuum. They include a range of waves such as radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. These waves are characterized by oscillating electric and magnetic fields and travel at the speed of light.