Generalized reciprocity is the proffering of a gift without the expectation of immediate return. Unselfish sharing falls within this category, as does the idea of "paying it forward," when the value of the exchange is often entirely social and non-tangible.
Balanced reciprocity demands an immediate reward for giving. One common modern example is the baby shower, where a guest is expected to bring a gift in exchange for sharing a meal and social interaction. A guest may choose not to bring a gift but they risk losing social credit among their peers.
Negative reciprocity implies that one side loses in the exchange or receives less than they expect. Cheating, manipulation and hard bargaining are often involved in negative reciprocity, although taking things by force is another form.