In the context of brewing, gluten free refers to the use of ingredients that do not contain gluten from the onset. This includes ingredients such as sorghum, honey, millet, buckwheat, etc. It would exclude beer that use barley, wheat and rye (for example). Note: if gluten reducing enzymes, such as the commercially available product 'Clarityferm' are used on the gluten containing ingredients, that is commonly known as "gluten reduced" beer.