A cross-sectional study is a type of research design that examines data from a population at a single point in time. This method allows researchers to assess the prevalence of certain characteristics, behaviors, or health outcomes within a specific group. For example, a study might look at the health status of adults in a city to understand how many people have diabetes at a given moment. These studies are often used in fields like epidemiology and social sciences because they are relatively quick and cost-effective. However, they do not provide information about cause-and-effect relationships, as they only capture a snapshot rather than changes over time.