Breathing or respiration refers to the process by which organisms inhale oxygen from their environment and exhale carbon dioxide back into it.
Inhalation/Inspiration: The act of drawing air into lungs by expanding chest cavity volume.
Exhalation/Expiration: The act of pushing out air from lungs by decreasing chest cavity volume.
Respiratory System: The body system that includes your lungs and airways, which work together to take in oxygen and expel carbon dioxide.