The 2010 Census is part of the Decennial Census program mandated by the US Constitution. The decennial census is used for apportioning Congressional seats, as well as many other purposes, such as demographic research, allocating funding, and informing public policy. The 2010 Census had only 10 questions. They covered these topics:
American Factfiner is the Census Bureau's main portal for accessing Census data. A new version of American Factfinder was released in January 2011. Data sets will be migrated from Legacy Factfinder to the new Factfinder through fall 2011. Legacy Factfinder will go dark in January 2012.
For help identifying census geographies, e.g. all census tracts in a place