A biosignature refers to any substance or pattern that indicates the presence of life. This can include organic molecules, isotopic ratios, or specific chemical compounds found in environments like soil, water, or the atmosphere. Scientists study biosignatures to identify signs of past or present life, especially in extreme environments on Earth and other planets. In the search for extraterrestrial life, biosignatures play a crucial role. For example, missions to Mars and the moons of Jupiter and Saturn aim to detect biosignatures that could suggest microbial life. Understanding these signatures helps researchers explore the potential for life beyond our planet.