What is wild yeast in beer?

It is the naturally existing yeast in the air. For example Liefmans Goudenband is made in open vats, and exposed to the wild yeast cells that are naturally present in the air. The microflora found in the air of Oudenaarde (Belgium) make Liefmans a unique beer. It is then left to mature for 4 to 12 months in the cellar. Taste it by clicking http://beermyguest.ch/liefmans-goudenband-75cl/