The US Census is completed every 10 years. Very simply, it counts the number of people living in the United States and its territories.
The US Constitution (Article 1, Section 2) requires the country to compete this census every 10 years.
It is very important that each person completes the 2020 Census. First of all, it's required by law. However, it also plays a role in how funding and services are distributed across the country -- things like funding for schools, roads, and public safety. In addition, it determines how seats in the US House of Representatives are apportioned. States also use the Census data to figure how state legislative representation is distributed across the state. Census data is used for many other purposes -- both in the public and private sectors.
See the video from the US Census Bureau below for more information.
Information gathered from US Census Bureau website: https://2020census.gov/
If you are a student and are unsure about how you should fill out the Census form, see the Important Information for Students--COVID-19 Closure tab for important information.