Most documents filed to or created by a government agency are considered public documents. These include vital records (birth and death certificates, marriage and divorce licenses), criminal records, court records, professional licenses (such as medical, law, and driver's licenses), tax and property records, reports on publicly-traded companies, and FOIA or FOIL-able documents related to the operations of federal, state, and city government agencies (e.g. the FBI, the New York State Department of Corrections, or the NYPD).
Access to public records varies from state to state, by the type of record you are searching, and by the currency or age of the record. In general, when it comes to vital records, older documents (such as the birth certificate of a person who is now deceased) are more likely to be public, as in many states privacy laws restrict access to the vital and criminal records of living persons.
Ease of access to public records also varies; some are available online, while others are only available in hard copy and require the submission of a snail-mail request to the specific government office in which they were filed. For business, court, tax, and property records, more current documents (1970s-present) may be easier to come by, as the are more likely to have been digitized.
This page includes links to public record documents portals, as well as links to some commonly requested or NYC-specific agencies. For more information on filing a public records request from an agency that does not make its documents searchable online, see the FOIA and FOIL page of this guide.