What is the reason for the presence of a large number of islands in the Pacific Ocean?

A huge number of islands were formed in the Pacific Ocean for the reason that the tectonic plate of this ocean collides with different continental and oceanic tectonic plates from all sides. At the site of the collision of these plates, a high volcanic activity is observed, and then underwater volcanoes form islands. This explains the fact that most of the Pacific islands are located along the borders of this ocean, and not in its central part.