Style of improvised theater in which short and typically unrelated scenes are played. As opposed to Long Form , Short Form Improv is often more gimmickey and more based on silly games or handles, and less based on solid narrative and characters.
Both styles of Improv (long form and short form) have their zealots. There should be no discussion about which is best - both can be fun, both can be rewarding, and preference is based on personal likes or dislikes.
Longform and shortform are the yin and yan of improv: opposite, equal and complementary -- (found on www.YesAnd.com bulletin board)