In journalism and public relations, a news embargo or press embargo is a request by a source that the information or news provided by that source not be published until a certain date or certain conditions have been met. The understanding is that if the embargo is broken by reporting before then, the source will retaliate by restricting access to further information by that journalist or his publication, giving them a long-term disadvantage relative to more cooperative outlets. They are often used by businesses making a product announcement, by medical journals, and by government officials announcing policy initiatives; the media is given advance knowledge of details being held secret so that reports can be prepared to coincide with the announcement date and yet still meet press time. In theory, press embargoes reduce inaccuracy in the reporting of breaking stories by reducing the incentive for journalists to cut corners in hopes of "scooping" the competition.
Embargoes are usually arranged in advance as "gentlemen's agreements". However, sometimes publicists will send embargoed press releases to newsrooms unsolicited in hopes that they will respect the embargo date without having first agreed to do so — the phrase "For Immediate Release" often found at the top of press releases indicates that the information in the release is not embargoed.
News organizations sometimes break embargoes and report information before the embargo expires, either accidentally (due to miscommunication in the newsroom) or intentionally (to get the jump on their competitors). Breaking an embargo is typically considered a serious breach of trust and can result in the source barring the offending news outlet from receiving advance information for a long period of time.
News embargoes are one of several ways a source has of influencing media presentation of the information they provide; others include providing information "on background" or "not for attribution", limiting or providing "access", or even direct government or market intervention against the reporters or media company. (See confidentiality terminology in journalism for a full discussion of these.) The manner in which journalists react to these and other attempts to influence coverage are a matter of journalistic ethics.

Examples of embargoes
News embargoes are commonly applied on information of health-related news regarding upcoming medical journal articles. All major medical journals, including the New England Journal of Medicine, the Journal of the American Medical Association, and The Lancet, have publication embargoes.
The JAMA embargo probably dates back to the editorship of Morris Fishbein, from 1924 to 1949, and holds until 15:00 Central Time on the day before the cover date of the issue. Journalists who agree to not publish (in print, on television, on radio, or via Internet) until that time the information contained in a manuscript to be published by the journal receive advance copies of the journal by mail during the week before publication. For selected articles, press releases and news release videos are also prepared by science writers and released to journalists during that week.