The Social Security Death Index refers to the database that is created from the U.S. Social Security Administration's Death Master File. The database contains genealogical information, including name, birth, date of death, Social Security number and the decedent's last known address.
The database lists every person who died from 1936 onwards, as long as his death was reported to the SSA in addition to having a Social Security number. As of 2014, the Death Master File contains over 89 million records and is updated weekly. If a person's name is absent from the database, that does not mean that the person is alive, since the records can be inaccurate.