Thermochromic materials change color in response to temperature variations. This phenomenon occurs because the molecular structure of these materials alters when heated or cooled, affecting how they absorb and reflect light. Common examples include certain types of inks and dyes used in products like mood rings and temperature-sensitive labels. These materials have practical applications in various fields, including packaging, textiles, and electronics. For instance, thermochromic inks can indicate if a product has been exposed to excessive heat, while clothing made with these materials can change color based on body temperature, adding a unique visual element to fashion.