A sievert (Sv) is a unit of measurement used to quantify the biological effects of ionizing radiation on human health. It helps assess the potential risk of radiation exposure by considering the type of radiation and the sensitivity of different tissues in the body. One sievert represents a significant dose of radiation that can lead to serious health effects, including an increased risk of cancer. For practical purposes, smaller doses are often expressed in millisieverts (mSv), where 1 Sv equals 1,000 mSv, making it easier to discuss everyday exposure levels, such as those from medical procedures or natural background radiation.