Currently, the Census is completed by questionnaire, occurs in different intervals, and asks a variety of questions based on the survey. Prior to 2000, short-form and long-form surveys were administered. Every person in the United States received either one at random. In 2000 and going forward everyone was sent the short-form. Questions from the long-form and other surveys were developed into the American Community Survey.
American Community Survey
The American Community Survey is a longer questionnaire that uses sampling techniques to provide an understanding of American households. The surveys are administered every one, five and ten years. Each cycle provides a unique set of questions and is sent to a random sampling of people. The infographic below titled Women's Earnings was created from information collected in the 2019 American Community Survey.
The Decennial Census is a short questionnaire that each American household is required to complete and occurs every ten years. Historically, it used to be presented as both a long and a short-form. Currently, only the short-form is used.
Below is an example of the 2020 Decennial Census questionnaire.