Journalism sourcing is the practice of identifying a person or publication that gives information. In journalism, a source is a person, publication, or other record or document that gives timely information. Outside journalism, sources are sometimes known as "news sources". Examples of sources include official records, publications or broadcasts, officials in government or business, organizations or corporations, witnesses of crime, accidents or other events, and people involved with or affected by a news event or issue.

Source: http://en.wikipedia.org/wiki/Source_(journalism)