Capsules are usually made from animal source gelatin or, if vegetarian, from starches like plant fiber derivatives. This allows them to dissolve from anywhere from almost instantly to within a matter of 15 to 30 minutes. Capsules are widely used in supplements because they are easy-to-swallow and break down quickly in the stomach, and some can be taken apart, giving you the option of mixing the powdered contents with a food or beverage which can be an advantage for children or others who have difficulty swallowing pills.
Drawbacks: Capsules cost more than tablets and have significant space and potency limitations since their powdered contents cannot be compressed to a significant degree. Since capsules are not air-tight, their shelf-life is shorter than tablets.