Thermochromism is a phenomenon where materials change color in response to temperature variations. This occurs due to the structural changes in the molecules of the material, which can affect how they absorb and reflect light. Common examples include certain types of inks and plastics that shift color when heated or cooled. Thermochromic materials are often used in various applications, such as temperature-sensitive products, thermometers, and clothing. These materials can provide visual cues about temperature changes, making them useful in both practical and decorative items.