The geographical feature characterized by flat plains and vast grasslands is known as a savanna. Savannas are typically found in tropical and subtropical regions, offering a unique ecosystem that supports a diverse range of wildlife and plant species. These regions transition between forest and desert, and are characterized by scattered trees and grasses. Famous examples include the African Serengeti, where large herbivores and predators coexist in their natural habitat, illustrating the complexity of savanna ecosystems.