Newspapers also follow this format - in most countries the "serious" news being placed at the beginning of a publication, with less serious issues such as TV listings, sports and letters being placed later in the publication.
However, the advent of 24 hour TV news stations such as CNN, BBC World and Euronews, along with the massive expansion of the internet, has made significant changes to the ways that media construct their reports. A vast amount of effort is now put into gathering news, and once consequence of this is that news media are no longer able to manage the flow of news as comprehensively as in the past, nor to restrict access to what information the public will become privy to.
Throughout history individuals, organizations and governments have sought to control public access to information. In this they have been sometimes aided and sometimes obstructed by the organs of the media which deliver that information.