Petrichor is the pleasant, earthy scent that arises when rain falls on dry soil. This unique aroma is primarily caused by a compound called geosmin, which is produced by soil-dwelling bacteria. When raindrops hit the ground, they release this compound into the air, creating the distinctive smell that many people associate with fresh rain. The term "petrichor" was coined in the 1960s by two Australian researchers, Isabella A. Gordon and Richard G. Thomas. They combined the Greek words "petra," meaning stone, and "ichor," which refers to the fluid that flows in the veins of the gods in mythology. This name reflects the connection between rain and the natural world.