an official count of a population / In ancient Rome, the census was “a registration of the population and their property that was used for assessing taxes.”
There are six biblical instances of a census of the Jewish people having been taken.
In the fourth month after the Exodus, when the people were encamped at Sinai. The number of men from twenty years old and upward was then 603,550 (Exodus 38:26).
Another census was made just before the entrance into Canaan, when the number was found to be 601,730, showing thus a small decrease (Numbers 26:51).
The next census was in the time of David, when the number, exclusive of the tribes of Levi and Benjamin, was found to be 1,300,000 (2 Samuel 24:9; 1 Chronicles 21:5).
Solomon made a census of the foreigners in the land, and found 153,600 able-bodied workmen (2 Chronicles 2:17,18).
After the return from Exile the whole congregation of Israel was numbered, and found to amount to 42,360 (Ezra 2:64).
A census was made by the Roman government in the time of our Lord (Luke 2:1). Mary and Joseph travelled to Bethlehem of Judah for this census.
See: When did the Luke 2 census occur? Is there a biblical error?