Throughout its history, Earth has had four different atmospheres.

An excerpt from the article 25 facts about Earth

At first, it was surrounded by a primordial atmosphere, which consisted of the remains of proto-planetary gas, mainly hydrogen and helium. As the proto-planetary disk thinned, these gases escaped from Earth's atmosphere into space.

After that, the first atmosphere appeared - it was created from degassed matter that fell to Earth during cosmic bombardments. Most (about 80 percent) was water vapor. The remaining gases were: carbon dioxide, methane, hydrogen sulfide, ammonia, carbon monoxide, and nitrogen. The first atmosphere was formed about 4 billion years ago and the high content of greenhouse gases made the Earth a very hot place.

The second atmosphere was formed when most of the water vapor condensed and fell to Earth as precipitation. The most common gas in the atmosphere at that time was carbon dioxide.

The third atmosphere was created thanks to the first living organisms, inhabitants of the oceans - which began to produce oxygen in the process of photosynthesis. Since then, oxygen has been continuously present in the atmosphere and provides living conditions for most organisms.