There are two types of censuses: The nominative census, which provides such detailed information, and the numeric census, which only indicates the number of inhabitants sorted by district, age, profession, etc.

Besides Parish Registers, censuses constitute the most important genealogical source. Since family members are listed together, along with their age and sometimes place of birth, locating the right family often means a major step forward in the genealogical search. Many of the censuses contain information on the living conditions of the listed individuals, as well. The censuses also constitute important source data for researchers in many other fields.