There isn't a single, definitive answer to how many crustal plates there are. It depends on how you define "plate" and how granular you want to be.

Here's why:

* Major vs. Minor Plates: There are 7 major plates (North American, South American, Eurasian, African, Indo-Australian, Antarctic, and Pacific) and many smaller, minor plates.

* Microplates: Some plates are so small they are called microplates.

* Continuously Evolving: The Earth's plates are constantly moving and interacting, which can create new plates, split existing ones, or merge them together.

So, a more helpful answer is:

* Major Plates: 7

* Minor Plates: Several dozen

* Microplates: Hundreds

In total, there are probably hundreds of plates on Earth, with varying degrees of size and activity.