Air is the Earth's atmosphere. Air around us is a mixture of many gases and dust particles. It is the clear gas in which living things live and breathe. It has an indefinite shape and volume. It has no color or smell. It has mass and weight. It is a matter as it has mass and weight. Air creates atmospheric pressure. There is no air in the vacuum of the cosmos.
Animals need the oxygen in the air to live. In the human body, the lungs give oxygen to the blood, and give back carbon dioxide to the air. Plants need the carbon dioxide in the air to live. They give off oxygen that humans can breathe again.