The American Community Survey (ACS) Public Use Microdata Sample (PUMS) files are a set of untabulated records about individual people or housing units. The Census Bureau produces the PUMS files so that data users can create custom tables that are not available through pretabulated (or summary) ACS data products.
PUMS files, in contrast to the summary tables and profiles available in American FactFinder, include population and housing unit records with individual response information such as relationship, sex, educational attainment, and employment status. The PUMS files are accessible via American FactFinder, the Census Bureau's FTP site, and DataFerrett. Statistical software is needed to use the PUMS files from American FactFinder and the FTP site.
For more details visit: PUMS Documentation