Curies are units of measurement used to quantify radioactivity. One curie is defined as the amount of radioactive material that produces 3.7 x 10^10 disintegrations per second. This unit is named after Marie Curie and Pierre Curie, who conducted pioneering research on radioactivity in the early 20th century. The curie is often used in fields such as medicine, nuclear physics, and environmental science to measure the activity of radioactive substances. It helps scientists and medical professionals understand the level of radiation exposure and its potential effects on health and safety.