The 2020 Census is an enumeration of every person residing in the United States.
It is conducted by the U.S. Census Bureau under the Department of Commerce. While the 2020 Census is their most important operation, it is far from the only information that they gather on a yearly basis.
the u.s. census bureau conducts over 130 household surveys each year
The most common household survey is the American Community Survey (ACS) that occurs every year. The survey goes out to about about 1 in 38 households each year and is significantly longer than the decennial census. All the surveys will continue operations through 2020.
How to identify a census employee can be found here.
A list of all the surveys can be found here.