Cicadas are insects known for their distinctive sound, produced by males to attract females. They belong to the order Hemiptera and are found in various parts of the world, particularly in warm climates. Cicadas have a unique life cycle, spending several years underground as nymphs before emerging as adults to mate and lay eggs. There are two main types of cicadas: annual and periodical. Annual cicadas appear every year, while periodical cicadas, like the 17-year cicada, emerge in large numbers after spending 17 years underground. These insects are harmless to humans and play a role in the ecosystem by aerating the soil and serving as food for various predators.