The two countries of Haiti and the Dominican Republic are located on the island of Hispaniola in South America. Haiti occupies the western third of the island while the Dominican Republic occupies the eastern two-thirds.
It is not an island by itself but it shares the island of Hispaniola with Haiti. The Dominican Republic occupies the eastern 2/3 of the island of Hispaniola, between Cuba and Puerto Rico. The western 1/3 of the island is Haiti. Yes It is part of an island it shares the island with Haiti