The element with the chemical symbol ‘O’ is oxygen. Oxygen is a vital element for life on Earth, as it is a key component required for respiration in most living organisms. It is also essential for combustion processes. In its gaseous form, it constitutes about 21% of the Earth’s atmosphere. Oxygen exists as diatomic molecules (O₂) and can also form various compounds, such as water (H₂O) and carbon dioxide (CO₂). Additionally, it plays a crucial role in various biological and chemical processes, including photosynthesis, whereby plants convert light energy into chemical energy.