A biographical dictionary is a reference book that provides concise information about notable individuals. It typically includes details such as a person's birth and death dates, significant achievements, and contributions to their field. These dictionaries can cover a wide range of subjects, including politicians, scientists, artists, and historical figures. Biographical dictionaries are useful for researchers, students, and anyone interested in learning about influential people. They often organize entries alphabetically and may include additional features like indexes or bibliographies. Some well-known examples include the Dictionary of National Biography and American National Biography.