The types of exploitation of children are not reducible to a common denominator; they differ in severity and in significance. The most repulsive include the sweat-shop system, bondservice, maids-of-all-work in a situation of virtual bondage, and prostitution. Children are highly exploitable, and in certain circumstances their vulnerability is manipulated to their lasting disadvantage. Children are sold into slavery, trained to be criminals, used for human organ transplants, forced into prostitution, abandoned, used for force labour, forced to work in inhuman and dangerous conditions and enlisted into armies.