Why are infrared waves often called heat waves?

Infrared waves, when they encounter an object, cause the atoms and molecules within that object to vibrate. These vibrations increase the object's internal energy and temperature. This is why infrared waves are often called heat waves. Electromagnetic waves carry energy, meaning they also carry momentum and exert radiation pressure. However, the energy and momentum transported are not continuously distributed across the wavefront; instead, they are transported by photons in discrete packages.