WebCite® (www.webcitation.org), which used to be a member of the International Internet Preservation Consortium, is an on-demand archiving system for webreferences (cited webpages and websites, or other kinds of Internet-accessible digital objects), which can be used by authors, editors, and publishers of scholarly papers and books, to ensure that cited webmaterial will remain available to readers in the future. If cited webreferences in journal articles, books etc. are not archived, future readers may encounter a "404 File Not Found" error when clicking on a cited URL. Try it! Archive a URL here. It's free and takes only 30 seconds.
A WebCite®-enhanced reference is a reference which contains - in addition to the original live URL (which can and probably will disappear in the future, or its content may change) - a link to an archived copy of the material, exactly as the citing author saw it when he accessed the cited material.
JMIR authors citing webpages, PDF reports available online, and other web-based references used to be asked to add a WebCite link to their references, however, since December 2018 this is no longer mandatory due to WebCite phasing out its service to the community.
A WebCite®-enhanced reference contains the traditional elements of a reference (e.g. author and title of the cited webpage, if known), the cited URL, and a WebCite® URL.
Plunkett, John. "Sorrell accuses Murdoch of panic buying", The Guardian, October 27, 2005, URL: http://media.guardian.co.uk/site/story/0,14173,1601858,00.html, Archived at http://www.webcitation.org/5Kt3PxfFl on December 4th, 2006.