Baking chocolate is typically prepared in unsweetened, bittersweet, semisweet and sweet varieties, depending on the amount of added sugar.

Recipes that include unsweetened baking chocolate typically use a significant amount of sugar. Bittersweet baking chocolate must contain 35 percent chocolate liquor or higher. Most baking chocolates have at least a 50% cocoa content, with the remaining content usually being mostly sugar.

Sweet varieties may be referred to as “sweet baking chocolate” or “sweet chocolate”.[6] Sweet baking chocolate contains more sugar than bittersweet and semisweet varieties, and semisweet varieties contain more sugar than bittersweet varieties. Sweet and semisweet baking chocolate is prepared with a chocolate liquor content between 15 and 35 percent.

Info and image from Wikipedia