Most people, when asked what Consciousness is, will reply that it is the state of being awake. That is most certainly true, for that it is. But when people reply with this answer, they are almost always talking about the state of being physically awake. This is not the kind of Consciousness we're talking about here. For one could be physically awake and still be largely or totally unconscious in their overall awareness.
If we consult a standard dictionary of encyclopedia, we find that Consciousness is commonly defined as "the characteristics of a being generally regarded to comprise qualities such as subjectivity, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment."
Subjectivity means one's own perceptions of one's existence. Self-awareness means that one is able to ponder and comprehend the fact that one is actually aware of one's own characteristics and perception - being aware that you are aware, so to speak. Sentience is the capability of having perceptions and feelings. Sapience is discernment or wisdom - the ability to know that some things are more desirable than others if a particular condition or outcome is preferred.
This definition of Consciousness does an overall good job of accurately describing the condition. But we could express the basic definition of what Consciousness actually is in a more concise and simplistic way. Keeping in mind and building upon the popular dictionary definition, one could say that at its essence, Consciousness is the ability of a being to recognize patterns and meaning with respect to events taking place, both within oneself and in the external realm in which the self exists and operates.
This ability is the fundamental driving force of all Creation. It could be said that all of Creation itself IS Consciousness in various forms and states of awareness. Consciousness is required for matter to exist. Consciousness creates the observable effects we perceive in our world. Everything that exists in the seemingly "external" domain first exists as a construct in Consciousness before becoming manifested through form.
Consciousness, or the lack thereof, is the agency responsible for the conditions in which we find ourselves, in all times and all places. It is responsible for 
the current conditions of Earth and all the people and animals living upon this planet. Almost anyone who is asked the question "Do you think that things are perfect just the way they are going on this planet?" will respond "No" and say that they think that things could, and should, be much better compared to the way things currently are. Yet, while most are aware that something is not quite right with what is going on here, few people can cut to the core of the problem and recognize it for what it is that causes all the suffering and negativity human beings seem to perpetually experience on Earth.
The root of all the problems we experience, indeed of all the problems humanity has ever experienced, lies in the Consciousness of the individual human beings alive on this planet at any given time. Our apparent inability to alleviate our suffering, brought about by the manifestation of these problems, is always caused by one thing: an imbalance in Consciousness which leads to a diminution in conscious awareness. The less Consciousness we have, the less we recognize the patterns of behavior and event which lead to suffering. When we work to increase our Consciousness, we develop more of the ability to recognize patterns which lead to negative results, and we therefore become more capable of avoiding negative outcomes and creating positive results and conditions.
The purpose of our collective existence is to steadily increase our conscious awareness until we can master our ability to develop sapience, the ability to make correct conscious choices, utilizing proper discernment, to bring about positive effects, conditions, and relationships in our world. This process is the goal of the spiritual journey and the manifestation of the Will of Creation. It is the Evolution of Consciousness.
At the current time in which we live, humanity has arrived at a critical point in this evolutionary journey. Human beings simultaneously possess (perhaps for the first time in our existence, to this degree) the ability to create a veritable paradise on Earth - in which the suffering of the beings of this world could be virtually eliminated once and for all - and the ability to destroy not only all human life, but the lives of every living thing on the entire planet. One situation is miraculously promising, the other incredibly horrific. The fact that they both exist in simultaneous juxtaposition with each other certainly makes the time in which we are living quite interesting and exciting.
While these two potentialities are competing with each other, so in fact is the increase and decrease in human Consciousness. We are seeing Consciousness growing with amazing acceleration and in greater numbers of human beings than at, perhaps, any other time in history. Side-by-side with this process, we are also seeing the Consciousness or more people hijacked, shut down, and quite possibly destroyed by the forces of Fear and Evil than at any other time in history as well.
What is required to transcend the conditions of suffering in which we currently find ourselves is an increase and acceleration of this process of conscious awareness on the level of the individual, and then on a global level. This global awakening will only take place once enough individuals have made enough conscious change within themselves in order for these energies to spill over into the collective Consciousness of humanity, upon which time this change will accelerate even faster and become habituated.
While it is true that we are going through a dark period before this light of awareness emerges in its full presence, I prefer to see the situation as hopeful rather than bleak. More and more people are becoming Conscious, Aware, and AWAKE. The change in Consciousness, this paradigm shift, IS happening, and nothing can hold it back, for it is our birthright.
When we emerge out of this evolutionary cocoon, our metamorphosis will be complete, and we will awaken to a new day and a new world. The end of the journey will join with a new beginning to complete the circle. And we will truly know ourselves for the first time.