Plants release oxygen during photosynthesis. As they convert sunlight into chemical energy, they absorb carbon dioxide from the atmosphere and water from the soil. The process transforms these inputs into glucose and oxygen, the latter being a byproduct. This release of oxygen is vital for life on Earth, as it provides the necessary element for nearly all living organisms to breathe. Photosynthesis not only sustains plant life but also contributes significantly to the planet's oxygen levels, supporting the ecosystem and helping to regulate atmospheric composition, which is essential for maintaining life on Earth.