Microorganisms are the oldest life forms on Earth. They are ubiquitous and play pivotal roles in creating the conditions and maintaining the ecological functions of our inhabitable planet. The discipline of modern geobiology is microorganisms centric, which aims to understand the life evolution and its interplays with the changing Earth with a goal to explore the possibility of life present elsewhere in the solar system. This course will teach students major progresses in the development of the modern geobiology discipline and highlight prominent figures who played fundamental roles in different stages of its growth.