It is easy to distinguish what it is from what it is not, just by telling them apart. Since this is the simplistic, empirical approach while studying existence. Yet what exactly is existence itself? How or where does existence exist? Is existence limited to the human existence, human cognition, or the humankind? Yes, because all living beings are defined by existence, just because the term ‘being’ implies to be, to exist. However, the term ‘real’ implies the same. Because the concept ‘existence’ has a multitude of terms defining it, and now we have to consider them while studying existence in all details. And as you notice, we are not looking for a superficial, empirical study, because we already have one, since we already know that everything that exists exists and everything that does not exist does not exist. We want more, we want a comprehensive study of existence, from all perspectives: existential, rational, living, interconnected, social, objective, analytical, created, consensual, cognitive, natural, mathematical, consensual, developmental, scientific, fiat, empirical, subjective, philosophical, ideological, highjective, accurate, algorithmic, legal, and correspondent. Only that, from all these distinct perspectives of existence, we end up with a distinct type of existence, as we have to consider these. But what exactly is there escaping the senses of perception of all living beings in this world? The nonexistent, certainly. And what exactly exists and takes place beyond existence itself? Again, it is the nonexistent. Yet this is the case only for us and from our perspective, since existence is relative to any observer. You have one existence defining you, and it is your own existence. And in this manner, you may exist even on your own, and you still exist, for yourself. Yet for others, if they never encounter and never interact with you directly and implicitly, then you do not exist for them, you are simply part of the inexistent according to them, and so are they for you, from your own perspective. Because there might be zillions of worlds and realities similar to ours, but if they never interact with us, then they never exist for us, while we never exist for them. And this is the case for all realities, because nothing exists objectively at the exterior of any reality, not even the concept of ‘exterior’ itself. We already notice how existence is capable to define everything as existing or not, in this simple Boolean manner. And this is the case because existence stands towards the base of our world, defining everything within to exist, to be real, or simply to be, since it is the same concept. However, when you try to define existence itself, you cannot, since there is not much below it to form a meaningful base of knowledge defining it, but only the absent, the missing, the unreal, or the nonexistent, distinguishing existence trivially, by contrast. This is your only mean to define accurately existence now, as being different from the nonexistent, and this is why you end up with a Boolean depiction for existence. To be or not to be. But never to be and not to be. While existence defines everything else in a similar Boolean manner: you either exist or you do not. You either interconnect with others being part of their existence, or not. You are either alive, or not. You are either fulfilling throughout life, or not. Throughout this book, we study existence entirely, through accurate facts, from all perspectives and in all circumstances, in order to understand it accurately. Furthermore, we use existence to define, understand, and explain everything related to humans and human life. And since existence stands at the base of everything that exists, this accounts for everything.