Mood rings are jewelry items that change color based on the temperature of the wearer's skin, which is believed to reflect their emotional state. Typically made of a thermochromic material, these rings contain a liquid crystal that reacts to heat. The color changes are often associated with different moods, such as calmness, excitement, or stress. Originally popularized in the 1970s, mood rings became a trendy accessory for expressing feelings. While they are often seen as fun and decorative, the science behind them is based on the idea that body temperature can fluctuate with emotions. Today, mood rings remain a nostalgic symbol of self-expression and personal connection.