1. Waves

One of the most interesting phenomena in physics is wave phenomenon. Consider the nature of light: "Is light a wave phenomenon or a particle phenomenon?" If light is a particle phenomenon, then the particle shall be well-defined in a 'small' region in space. This is the essential feature of a particle, its localization in a well-defined "small" region in space. However, practically, this particle interacts with its environment; for instance, it has a gravitational field that interacts with the earth, the moon, and the sun, etc. And this field, cannot be separated  from the particle since it spreads out into space. Real particles interacts via fields, and, in a sense, the field is the particle and the particle is the field (E.Hecht. Optics. Addison-Wesley, 1998).  Adequately, if  light is a beam of submicroscopic particles (photons) , they are by no means "ordinary" mini-ball classical particles.

In contrast to the localization feature of a particle, a classical traveling wave is a self-sustaining disturbance of a medium, which moves through space transporting energy and momentum which is non-localized. However, the waves are not continuous entities since the media supporting the waves are atomic. That is, counter-intuitive to the concept of ideal wave as a continuous entity that exists over an extended region. The only possible exception might be the electromagnetic wave,  which was first suggested by Einstein as the statistical manifestation of a fundamentally granular underlying microscopic phenomenon.