A '''matrix scheme''' (also known as a '''matrix sale''' or '''site''', and as a '''hellevator''', '''escavatorexcavator''' or '''ladder scheme''') is a [[business model]] involving the exchange of money for a certain product with a side bonus of being added to a waiting list for a product of greater value than the amount given.<ref name=oftpress>{{cite web|url=http://www.oft.gov.uk/news/press/2005/161-05 |title=Matrix Website Scheme stopped by Office of Fair Trading |accessdate=5 August 2006 |deadurl=yes |archiveurl=https://web.archive.org/web/20070314233701/http://www.oft.gov.uk/news/press/2005/161-05 |archivedate=14 March 2007 |df= }}</ref> Matrix schemes are also sometimes considered similar to [[Ponzi scheme|Ponzi]] or [[Pyramid scheme|pyramid]] schemes.<ref name =msn1>{{cite web | url = http://msnbc.msn.com/id/3078957 | title=$150 plasma TV site faces lawsuit | accessdate=5 August 2006|archive-url=https://web.archive.org/web/20070219081023/http://msnbc.msn.com/id/3078957/|archive-date=19 February 2007}}</ref> They have been called "unsustainable" by the United Kingdom's [[Office of Fair Trading]].<ref name =oftpress/> A matrix scheme is also an example of an 'exploding queue' in [[queueing theory]].
