What event in Earth’s history is known as the “Great Oxidation Event”?

The term “Great Oxidation Event” describes an important epoch in Earth’s history that began around 2.4 billion years ago. During this time, photosynthetic species began to appear and proliferate, which led to an increase in atmospheric oxygen levels. The atmosphere and oceans of Earth became oxygenated as a result of these species, including cyanobacteria, which started to produce oxygen as a consequence of photosynthesis.