Fusion Monsters are a special type of card in the Yu-Gi-Oh! trading card game. They are created by combining two or more specific monster cards using a Fusion Spell Card, such as Polymerization. These monsters often have enhanced abilities and higher attack points compared to their individual components. To summon a Fusion Monster, players must have the required monster cards on the field or in their hand, along with the appropriate Fusion Spell Card. Once summoned, Fusion Monsters remain on the field until they are destroyed or removed by other card effects, making them powerful assets in gameplay.