There are nearly an infinite number of "interfaces." You need to clarify the question: Interfaces to what?
2 types
CUI character user Interface
GUI Graphic user Interface
IDE And SATA
many types
Thousands of types.
there are many different types
how many types of slabs
How many types of brahmins?
HOW MANY TYPES OF ANALYSIS
There were 26 basic types and each had many sub-types.
6 types of government
Renminbe Renminbe Renminbe
how many types of guns are there in the world?
There are MANY types of biomes in the world.