Press releases typically start with the word 'Press release' to indicate to the journalists that it is a press release. As a result, no covering letter is needed. As soon as the journalists read the word press release, they know what can and should be done.

Next, it is announced that the news is "For immediate release", which means that the journalists can spread it as soon as they want to. Alternatively, there can be an embargo (or what Americans also refer to as 'lock up'): in that case, the journalists are kindly but firmly requested not to spread the news before the date (and usually the time) indicated. An example: even before a corporation's financial results are officially announced at a press conference, journalists traditionally receive a press release spelling out the full details, with an embargo inviting them to delay publication until after the press conference.