Corn syrup is a food syrup which is made from the starch of maize (called corn in some countries) and contains varying amounts of maltose and higher oligosaccharides, depending on the grade. Corn syrup, also known as glucose syrup to confectioners, is used in foods to soften texture, add volume, prevent crystallization of sugar, and enhance flavor. Corn syrup is distinct from high-fructose corn syrup (HFCS), which is manufactured from corn syrup by converting a large proportion of its glucose into fructose using the enzyme D-xylose isomerase, thus producing a sweeter compound due to higher levels of fructose. (source)