Astrobiology is the study of life in the universe. It asks a lot of "big" questions: How did life originate? Where else might we find life other than on Earth? How do we go about looking for it?
Astrobiologists study the extremes of life forms as we know them and the evolution of life on Earth. Combining those studies with our ever-growing knowledge of the universe, astrobiologists discern what extraterrestrial life might look like and what conditions need to be present for life to exist. In this way, astrobiology is intrinsically linked with the exploration of space and the discovery of exoplanets.