Too many words have been expended on explanations trying to prove one or the other of two contradictory ideas as to what is the nature of light. Mental acrobatics have even led to the promulgation of a new species, the wavicle (a combination of a wave and a particle) so as to cover up for the failure of modern physics to account for what seems basically an easily resolved paradox.
Photons have been described as wave packets, being able to travel like a wave and at the same time to exhibit particle properties. Photons have also been denied mass, in an effort to enable them to travel at light speed and they have been said to change direction when passing close to the edges of a slit so as to explain the presence of interference patterns while maintaining that photons are particles, not waves.
It seems entirely too easy, but there is a simple solution to all this trouble with the "dual nature" of light. It is to drop the requirement of contemporaneity of the dual manifestation. Who ever observed the two diverse manifestations of light at the same time? The truth is, no one did!
Now in order to consider the nature(s) of light in more detail, we should step back for a moment and try to illuminate the background, in and through which light travels and acts.
Space is is created by and consists of a network of unimaginable extension, of stable but virtual "dimension points". The dimension points establish the boundaries of space and build up, between themselves, a seething sea of pure energy, which has been called ether or aether and which I have called the energetic space background.
The energy that constitutes the aether is the result of "tension" between the members of this network of virtual dimension points. It is this energy that mediates the reality of our physical existence, the "matter" and "light" parts of the physical universe.
Particles of matter are formed from the energy of the space background by induction of localized chiral motion in the aether and so are cosmic accumulations of those same particles, forming stellar systems, galaxies and accumulations of galaxies.
Light may then be seen as a bridge between energy and matter, still being neither. While travelling, light is a disturbance of the energetic space background, often called a wave. Its velocity of propagation is dependent on certain characteristics of the energetic medium.
What we call photons or visible light, is probably a fine spray of miniscule energetic particles, far below the constituent particles of matter in energy content and size, but nevertheless with the basic conformation characteristic of matter, not unlike the effect we observe close to great waterfalls or on the ocean coast where the waves of water violently hit upon rocks that disrupt the flow, creating a fine mist of water droplets.
In a very similar manner, where an electromagnetic wave within a certain wavelength band hits particles of matter, the local scene is illuminated by a fine spray of countless photonic particles which allow us to perceive both the matter and the source of the wave.
The best interceptor of a stellar light source seems to be an atmosphere, as in addition to providing a screen of air molecules to "break" the electromagnetic wave and create the "photonic spray", it also serves to break up and distribute those photons more evenly, thus creating what we refer to as "soft light", making shadows much less sharp than they would be without.
An atmosphere also seems to provide a lens effect, allowing us to better perceive distant stellar sources of light. In fact, the sky should be perceived as dark or nearly so by an astronaut travelling in interplanetary or interstellar space.
To sum it up, light exists as a wave while travelling, and it exists as a photonic spray in any setting of direct observation. The reason we can observe the famous interference patterns in the double slit experiment is that the slits in the experiment let the waves pass, without breaking them up, and only at the end point where the interference pattern forms, is the wave stopped and gives rise to photons, which now show the pattern characteristic of a wave.