A nominal scale is a type of measurement used in statistics that categorizes data without any order or ranking. It simply labels different groups or categories, allowing for the identification of distinct characteristics. For example, categories like gender, blood type, or favorite color are all nominal data, as they do not imply any quantitative value or hierarchy. In a nominal scale, each category is mutually exclusive, meaning that an item can only belong to one category at a time. This scale is often used in surveys and research to classify responses, making it easy to analyze and compare different groups.