Yerba Mate is an infusion, made from the dried leaves of the yerba mate (Ilex paraguariensis) plant. Because it does not use the leaves of the tea plant Camellia sinensis it is not a true tea, but rather a tea-like beverage. It does, however, contain caffeine. Yerba Mate is the national drink in Argentina, also Uruguay and Paraguay, and is commonly enjoyed in other countries, particularly Brazil where it is called chimarrao.
Yerba Mate is prepared in a special fashion, using a gourd and a special straw, the bombilla for drinking. It is traditionally drunk in community, with the Yerba Mate passed around so that all can share from the same "cup."
Image of Yerba Mate from Wikimedia Commons.