Consciousness cannot be defined because it is an elementary quality. It can be described by enumerating its constituent factors, like knowing, feeling, and willing in their various forms.
Consciousness always belongs to an individual mind. Each one of us feel, think and wish individually. Thought and feelings cannot be given or shared or even bartered among different individuals.
Mental processes always keep changing, just like the waves in an ocean are in motion.
“The mind is the stream of consciousness”. (James)
Consciousness is selective. We do not attend to the overflow of sensations. We select and then react to them. Our five senses are the sources of our consciousness; their impressions give consciousness a continuity. It so happens that even while we are paying attention to something, we are not unaware of the surroundings. Our senses keep on carrying information to our mind and it in turn forms the margin of the consciousness.
The subconscious is working when we recognize a person met earlier. It consists of the traces saved form the impressions of the past. The subconscious retains the memories of the past. It helps in the development of emotions. Dreams are also considered as the act of subconscious.
Abnormalities in the personalities are due to the block/breach of continuity of consciousness.
While growing up as an individual we have to come to terms with a social model of personality, not all of our desires and passions are fulfilled. Those left unfulfilled are suppressed to unconscious mind, and these keep attacking onto the surface of consciousness in form of dreams, day-dreams, worry, slip of the tongue and the like. (Freud)
Human beings are aware of their environment and connect with it with the help of consciousness. This can be controlled with practices to command our senses so that they do not distract us from our motto/goal. It is a hard task but it can be attained. Once we command our consciousness we can command our whole being and come to terms with the energy that is flowing through all beings on this earth. Then there will be mutual harmony and peace. There will be solace. And this should be the ultimate goal of all human beings.