What is the essence of the breathing process?

The breathing process is necessary for every creature on our planet. Breathing is the process of obtaining oxygen and removing carbon dioxide from the body into the environment. For existence, all living beings need oxygen, which they receive by breathing.
The essence of respiration is the saturation of the blood with oxygen and the intake of carbon dioxide from it, obtained as a result of the vital activity of cells. Living things have different ways of obtaining oxygen from the environment, which also become more complicated as the level of development of a living organism increases.