The Island Address is a feature in Tomodachi Life. It's main purpose is to give the Island a unique name. Explorers received though StreetPass will state the name of their original Island. Clothes and hats received through StreetPass and/or SpotPass will display the name of the Island they came from (usually Nintendo Island in Spotpass) and will be able for purchase in Import Wear.
The Island Address consists of the island name, a 6 digit number code, an Isle name, and an Ocean name.