How did earths atsmophere change during the precambrian time?

During the Precambrian time, the Earth's atmosphere underwent significant changes. Initially, the atmosphere was mostly composed of gases like carbon dioxide, water vapor, and nitrogen. As photosynthetic organisms evolved, they started producing oxygen as a byproduct, leading to the Great Oxidation Event around 2.4 billion years ago, which gradually increased oxygen levels in the atmosphere. This shift in atmospheric composition had a profound impact on the evolution of life on Earth.