Consciousness is something that is undefined. Whenever you wish to define consciousness, you have limited it. Consciousness by default is subjective. Every experience that one has is within consciousness. That is why consciousness cannot be defined because whenever you want to limit or define the consciousness or give it a form, you are going out of the realm of consciousness.
Essentially consciousness is just a vibration, as experienced by a lot of people who meditate. The more you want to define it, the more you create a form out of consciousness. Scientists say that consciousness is created from the brain. However, near-death experiences have shown that the consciousness of people remains, even after the experience of death. In such cases, it has been seen scientifically also that the brain was actually dead, and so was the heart. There are many instances of people who came back from near-death experiences with vivid memories of their experience. This further validates that consciousness is able to live even outside of the body. There are experiences where blind children had some visions during near-death experiences, even though they were blind by birth. So how could they see stuff?
An experience of everything and anything is consciousness. It is the emotions of mother’s love, it is the pleasure of your favourite food and even the feeling of what it was like experience heartbreak.
There is an explanation about Access Consciousness that it is something like electricity and that your brain is a switch, not the generator of this electricity, just a switch of this electricity and this consciousness. So you may imagine it to be like an electric beam of light that is merged with the universal consciousness. That is why zen monks always experienced in deep Meditation the merging with the universe. And that is the state of ecstasy, where the individual eye, which is limiting you goes away. You have a feeling that you merged, that your true identity is your universal self. That is the universal consciousness.