* Volcanic islands are constantly forming and changing: Volcanoes are active geological features. New islands can be created by eruptions, while older ones can erode or even sink back into the ocean.
* Definition of "island" is variable: What constitutes an island is somewhat subjective. Is a small rock outcropping considered an island? What about a landmass that is only visible at low tide?
* Many islands have multiple origins: Some islands are formed by a combination of volcanic activity and tectonic plate movement.
However, we can say that a vast majority of islands around the world have volcanic origins. Volcanic islands are found in all the major ocean basins.
Here are some examples of island chains formed primarily by volcanoes:
* Hawaiian Islands
* Canary Islands
* Azores
* Philippines
* Indonesia
So, while we can't give a precise number, it's safe to say that volcanic islands are incredibly common and play a crucial role in shaping the Earth's geography.
