Public records are government documents open to public inspection. It is a popular tag because private and official U.S. government web sites will search for records pertaining to a particular individual or entity (as in most other countries).
While not all public records are available online, official U.S. government sites normally provide free access to those that are. Private sites usually charge for searching records but often use broader databases.
The type of information available in U.S. public records is wide-ranging. For businesses it includes SEC filings, names of officers and directors, and annual reports. For individuals the information may contain the value of a person's home, a list of their political contributions, criminal and civil court filings and death records. Whether a record and the information in it is public is determined by the laws of the federal government or the state keeping the record.