I was really hesitant on discussing this topic, maybe because of its own controversial nature or its lack of universal understanding. Nonetheless, after two years of reading about it both from a scientific and a spiritual point of view, I feel confident enough to give an informed opinion on what we know about it so far. With that being said, I believe our understanding of what we call life its so insignificant even to this day, that topics like consciousness will just escape our total comprehension for a long time.
However, even though I consider we cannot understand consciousness at this point in time, I do think we can experience it and grasp its overall magnitude. If you look up its definition in the dictionary you will find something similar to this:
"a person's awareness or perception of something."
And I would say that in a broad sense it is completely true. But consciousness goes beyond that as we will see in a moment.
The state of being a conscious being like ourselves correlates with the status of experience. We are conscious of everything that we can recognize as a thought, and therefore we can experience it. Consciousness is in that extent, everything and everyone we can experience inside of it. Let's say you are confused about what I am saying right now, you probably had a thought similar to "I don't understand anything of what he is saying" or "this guy is on drugs". Whatever it may be, you as a conscious being, were able to experience this thought in what we call consciousness. You didn't choose to think that thought, and that's an important point, as we don't choose what to experience, we just experience it. Even if they are physical sensations, objects, sounds, thoughts, smells, whatever they are, these are simply appearances in consciousness, as it is the only thing that we really know. Our actions are also experiences for our conscious mind, as we don't really choose them, nor the thoughts that preceded them. This is part of a topic I will cover later on "Free Will", but for the time being you should understand we are merely conscious observers of our thoughts and actions, as we don't choose them.
Just to rattle your brain for a while, let's say you went to a party recently and had to choose between a glass of wine or champagne. Let's say you went for wine. According to most people, it was your decision to go for wine, if you go back in time right now perhaps you think you could've chosen the champagne instead, but you didn't, you went with wine. This is the illusion of what we call "Free Will". You don't really know why you chose the wine, perhaps you are thinking "well I just wanted to get wine because I haven't drink it in a while" and yeah that may be true as an argument of why you did it, but the fact is you didn't choose to have that thought, you just experience it and went for wine. Why not champagne? Were you really able to choose to go for it? Did the thought appear? Maybe you were comparing both and decided ultimately for the wine. But you didn't, the thought emerged "I'll go for the wine" and you went for it. And that's ok, as we don't really choose any of what we experience in consciousness.
The "ego" often comes into play when we talk about consciousness. The ego, in my own words, refers to the separation of yourself from what you consider to be the outside world. Let's try it a simple example. Look at any object in your environment, if your ego is strong, you will feel a clear disconnection between this object and yourself. Maybe a feeling of yourself looking towards the outside world and recognizing an object that has nothing to do with you as its completely separate. This, however, couldn't be farther from the truth. Not only this object but also what you would call "your own body" are merely appearances in consciousness. They are not separate, as they appear in the same space. The feeling of distance, the sensation of having legs, a torso, arms, and even a head, are all related to our experience. Now close your eyes, and tell me what do you see. You'll probably say something like "I can't see anything cause I got my eyes closed", but you can, can't you? You are probably seeing small amounts of light coming through your eyelids. This experience is important to show you that consciousness is not located somewhere in your head. Your head is not your head, it's just another appearance you can recognize in consciousness. The point I am trying to get across here is that there is virtually no separation between any experience you can have, the feeling of having a head for example, and the feeling of seeing an object at a distance. Both of those are simply appearing and being recognized in the same space, consciousness.
Another important concept comes into play here, and that is Mindfulness. We can confirm we are conscious all the time, but not mindful. Mindfulness is about being aware of every thought and every feeling you are experiencing at a giving moment, and we are usually not. You are probably thinking about other stuff while reading this, you are conscious, but not mindful. The practice of "vipassana" or mindfulness meditation is about being aware of your experience at all times in a given moment. These can range from the sound of a car to the feeling of your arm itching, the memory you just had about a party, or maybe the sensation of sleepiness you are having right now. I won't get into the benefits of such practice but it is important to recognize the difference between being mindful and being conscious as we all are.
So you are probably really confused after reading all of this. Again I was at first and don't blame you at all. We are all taught to recognize ourselves as individuals, unique and distinct from everything that surrounds us. We are also taught that we are free, responsible for our actions and capable of choosing with our minds. It's scary to think of a world without punishments for killers or rapists and the illusion of free will serves to maintain the status of the current order. However, when we talk about the Ego and its dissolution, quicker pathways such as drugs can help you experience what it feels if you want to. Drugs such as LSD and mushrooms, don't inflict foreign or unknown effects on our brains but only increase the amount of activity inside of it. The Ego dissolution is one of the most relevant experiences one can have while on some of these drugs, and it refers to the state of oneness in the universe without distinction between your body and everything else. The illusions, sensations, and appearances people usually have on these drugs are also happening in the same space, in what you will now call consciousness. It is also believed that extreme meditators can get to those same states of mind without the need of drugs, however experiencing ego dissolution is not that far off from everyone, even after meditating for a short period of time it's possible to know to some extent what it feels like.
As you can see this is no easy topic to cover, as it challenges multiple of our core beliefs, but it brings much positive with it too. Mindfulness meditation is a great tool to start understanding the deeper meaning of what it is to be conscious and humble yourself as a mere observer or passenger of your experiences.
Consciousness is, after all, the one thing in the universe that cannot be an illusion.