Terra (The Trade Reference Currency, TRC) is the name of a possible "world currency". The concept was proposed by Belgian economist and expert on monetary systems Bernard A. Lietaer in 2001, based on a similar proposal from the 1930s.
The currency is meant to be based on a basket of the 9-12 most important commodities (according to their importance in worldwide trade). Lietaer opines this would provide a currency that wouldn't suffer from inflation:
The basic principle emerged from early concepts presented in an article in the French newspaper "Le Fédériste" on 1 January 1933. The idea to establish a "L'Europa – monnaie de la paix", in English "Europe - Money of peace", was given birth. The idea was enthusiastically picked up by Lietaer during an educational journey.