A dosimeter is a small device used to measure exposure to ionizing radiation, such as X-rays or gamma rays. It helps ensure the safety of people working in environments where radiation is present, like hospitals or nuclear power plants. By tracking the amount of radiation a person is exposed to over time, dosimeters help prevent harmful health effects. There are different types of dosimeters, including film badges and electronic dosimeters. Film badges contain special film that darkens when exposed to radiation, while electronic dosimeters provide real-time readings. Both types are essential tools for monitoring radiation levels and protecting workers' health.