first of all, let's use computers as a relative example. i am a computer programmer and there are many courses in computer phylosophy etc... i won't get too specific because it's unnecessary. humanity is trying to "replicate", like a human, a computer with artificial intelligence in the striving journey to be able to say that we are able to create a creator. we've accomplished nearly all in a computer (cyber) consciouness except AI, where this is the programming of free will/free thought to a computer. however, it is impossible for a computer to understand or compute a value of zero and creates a "concept of nothing" called a null value. until the computer can conceptually accept an absolute value of nothing, AI will not come about, because of the restrictions the concept itself imposes on the limits of free will/thought. The same goes with us in some regard. we cannot conceptually (or in thought) accept a value of absolute zero (not the temperature for those not following). We know what it means to have "nothing", like "i don't have any money" but we do this because we are able to compare against something. this is relative to all. you can say i don't know what it's like to have a ferrari, but you are only comparing that emotion to another relative figure like money.
the concept of nothing is to be able to 'accept' and without pre-comparison, unconsciously and consciously, but however to do this, there needs be apre-meditated (if you will) thought of planning all this thinking out. basically, you end up contradicting the very thing you want to do even before you attempt to do it. it is a necessary evil and if nothing was a person, he's already go you figured out.
say before the big-bang or God's hand in the creation of all, (whichever you want to believe), imagine standing there in the nothingness of nothing. now it's not black (you're thinking of black because of space, but space is another strain of water particles that are more dense, but more flexible than the densest form of matter-like transparent liquid-led). nothingness is not even transparent. if you can think of anything more transparent than transparent, there is a possibility that this is nothingness, or at least near. but it is conceptually impossible to imagine or comprehend non-color, non-position, non-time (which is not even pause or moving) it is beyond pause, yet thought somehow not stopped. these are the characteristics of nothingness.
it is meant to be greater than our consciousness for the sake of pure enjoyment as a mind-tease, it keeps us humble. so to summarize, here are some of the characteristics that you have to learn to grasp BEFORE understanding nothingness.
1. time: nothingness comes before pause, but is not rewinding or forwarding time. it is not moving either. it is stillness but is not still.
visual: a color beyond transparent but is not transparent as in the definition of a clear color, an empty color without particles (transparent contains particles)
position: relative to time. nothingness belongs somewhere, yet is nowhere. it has no departure point. try to conceive that. yet at the same time, it is everywhere.
now these are only 'physical' and somewhat 'mental' characteristics. sleep, in essence is the closest thing we have to experiencing nothingness.
but again: nothing, is something. it contradicts its own existence.