Candi sugar is a Belgian sugar product commonly used in brewing beer. It is particularly associated with stronger Belgian style ales such as dubbel and tripel. Chemically, it is an unrefined sugar beet derived sugar which has been subjected to Maillard reaction and caramelization. A common misconception is to consider this is the same as invert sugar while actual candi sugar is a subject of multiple complex chemical reactions happening during the Maillard process.
Also used as a priming sugar, to aid in bottle-conditioning, and carbonation, with the same benefits as listed above.