Biosignatures are observable signatures or signals that indicate the presence of life. In the context of astrobiology, biosignatures are used to search for signs of past or present life on other planets or celestial bodies. These can include physical structures, chemical compounds, or even environmental conditions that suggest the presence of living organisms. Researchers study biosignatures in various forms, such as microbial biomarkers, isotopic ratios, or unusual patterns in rock formations, to determine the habitability of a given environment and the potential for life to exist there. Understanding and identifying biosignatures is crucial in the search for extraterrestrial life and in assessing the potential for habitability in our solar system and beyond.