Is Zanzibar a city in Tanzania?

Zanzibar is a group of islands off the coast of Tanzania. Unguja is the main island, often called Zanzibar. Unguja is what most people are referring to when they say Zanzibar. Zanzibar City (is not a city - but a town) is the capital of the island. Yes, the whole group of islands belongs to Tanzania. The oldest part of Zanzibar - Stone Town- is a world heritage site.