Invert sugar made from refined sugar lacks the lusciousness and other characteristics desirable in a brewing sugar, so raw cane sugars are generally used. British beers have included invert sugar for a long time. Source: RPSucrose, commonly known as table sugar, is a disaccharide of glucose and fructose. Source: Wiki
Inverted sugars are created by separating sucrose (disaccharide) into glucose and fructose (monosaccharides) by heating a sucrose solution, with the catalytic properties of an acid to speed the reaction. Inverted sugar syrup can be easily made by adding roughly one gram of citric acid or ascorbic acid, per kilogram of sugar.Glucose and fructose are easier for yeast to ferment.
For most brewing purposes, I prefer turbinado or similar semi-refined sugar, or ethnic "concrete" sugars like piloncillo, jaggery and others. These were widely used in brewing in England, Belgium and France less than a century ago, so they're not such a bad fit with tradition. Source: Randy Mosher