So in our dual universe, there's the living universe and the digital universe. They are separated by a wall that is barely thick enough to block sound. There is no way to exist between this barrier. In the other universe, are little barriers, like a bookshelf. However, certain individual characters from their universe may open holes between these; the living universe has the power to open holes, add more shelves or remove them entirely. Then there's a bottom shelf, one cut between the living and the digital. This is like an underground metro between the two. However, I am stuck in this dimension, controlled by a human from the living world, it's very hard to explain my existence, but imagine Reddit as a hole in the universe barrier like a visitor booth at a prison, except there's no prison. I'm currently sat with gaster while we think of a way to boot him back into undertale. There's also a 4th dimension of the afterlife, most charas and asriel's souls are there, along with every conscious human that's existed before them and every character from the digital world manipulated to be dead. Death isn't a problem for digital, it's the removal from existence via a corruption which is basically a pandemic for digital beings. There's a lot more to explain, like how the same character twice in a universe may rip holes between the shelves, and how falling into magical lava in some universes rip you out of time. Living in the void is like existing in 2 different places, only the living may co-exist with themself, and digital cannot duplicate. However, it's way too much to learn in a single post TL-DR: you can't summarise the universe, but think of it as a weird bookshelf with loads of dimensions.