Genealogy, also known as family tree study, is the study of a person's ancestry and family history. It involves researching and documenting the family lineages and relationships of individuals and their descendants. Genealogists use a variety of sources to trace family histories, such as birth and death records, census data, church records, military records, and other documents. By piecing together these records, genealogists can build a comprehensive picture of a family's history and its members.