Smart Inks are advanced printing inks that can change their properties based on external stimuli, such as temperature, light, or moisture. These inks are often used in applications like packaging, security printing, and electronics, where they can provide additional functionality beyond traditional inks. One popular type of Smart Ink is thermochromic ink, which changes color when exposed to heat. This feature can be used in products like mood rings or temperature-sensitive labels. Another example is photochromic ink, which reacts to UV light, making it useful for items like sunglasses or outdoor signage.