Cold, often referred to as chill, is a sensation experienced when temperatures drop below a comfortable level for the human body. It can occur in various environments, such as during winter months or in air-conditioned spaces. Cold temperatures can cause physical reactions, including shivering, as the body attempts to generate heat. In nature, cold is associated with phenomena like snow, ice, and frost. These occur when water freezes due to low temperatures. Cold weather can also impact ecosystems, affecting the behavior and survival of various species, including animals that hibernate or migrate to warmer areas.