From Destinypedia, the Destiny wiki
This article is about the Void. For the ability, see Elemental Damage.
The Void is the name given to the substrate that underlies the physical universe; its precise nature is unclear, as it covers many areas. It is described as a place absent of Light, Darkness and matter, and is the source of Void energy, also called "Secret Light" for those such as the Guardians.
According to Ulan-Tan, the Void is simply another form of Light as it occupied time and space; this prevents the Darkness from entering through the Void. The Traveler is said to be able to travel through the Void to other places in the universe. It is also described as the infinities between spaces.
It is even described as being something that is addicting, that it was easy to use, but to let go was hard, to open a hole with the Void, and draw from the deep, described as being heavy too. Much like the Nightstalkers with their Shadowshots. Variks, The Loyal once asked if whether the Guardians really control the Void, or if the Void controls them.
All Guardians are able to access the Void through using their Light-based powers, and are able to experience the Void through meditating, This would be further supported on how the Void freed the mind of individuals. The Void has been said to have a faint scent of ozone associated with it.
Beyond the void lies other worlds, and that there are items that lets them access, there are even times where one is annihilated down to their particles and pulled through the void from one place to another reality.
The Vex are even able to have access to the Void too, through the means existing in time, like how The Undying Minds dwell within those voids, and how they can take the desired locations and remove them from the universe into the Void. And the Vault of Glass is described as "Timeless" and how Guardians that enter it are "Marked by the Void".
The Hive are capable of influencing the Void too, such as how Savathûn uses one of her long claws to stroke the Void and space-time groans beneath it. Taox said that their race escaped The Hungry Void to the planet Fundament. The Hive seem to be drawn to the masters of the Void too. This led the former Cabal Emperor Calus to hope that a Voidwalker might be able to lead them as one of his Shadows.
Servitors of the Fallen Houses are able to sense disturbances in the Void; when Mara Sov released her Harbingers on the House of Wolves, their Servitors reported a "strange taste in the Void" when the Harbringers attacked.
Former Cabal Emperor Calus once stared into the infinite void and how he described that it stared back at him, that he would become it's herald for when it comes to consume the universe once and for all. He also went on to describe it as the nothing, the absence of anything , which matches what other individuals described about the void. 
Some items can draw upon the essence of the Void when a Guardian dies and resurrects, to be used against their enemies. When there is little Light to draw on in certain areas, other items can draw power from the Void for their abilities.
Ikora stated that the Void is negation, and Guardians would become the ultimate negators, this would make sense with some of the Guardians abilities such as Titans' Suppression Grenades and Shadowshots which negates the abilities of their enemies. With using a Vortex Grenade, the target gets enveloped by the Void and is ripped apart and eaten away by it.
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