Stable isotopes are variants of chemical elements that have the same number of protons but different numbers of neutrons. Unlike radioactive isotopes, stable isotopes do not decay over time, making them useful in various scientific fields. They can be found in nature and are often used in studies related to geology, environmental science, and biology. Researchers utilize stable isotopes to trace processes and understand the origins of materials. For example, the ratio of stable isotopes in water can reveal information about climate patterns, while isotopes of carbon can help determine the dietary habits of ancient organisms.