many reasons, for example

• multidimensional arrays
• arrays of function pointers
• pass by reference of a pointer

Mostly because at the lowest level of computing (machine code and CPU instructions), pointers are the only method (that I know of) of any kind of indirection.

At the lowest level, there are 2 types of references:

• CPU registers
• memory addresses (pointers)

Every higher level language feature for memory management (references, objects, safe pointers, garbage collection, etc) is just an abstraction over raw pointers

Pointers themselves are really just abstractions over raw integers, whose sole purpose is to index into RAM

With that in mind, pointers to pointers are a natural consequence of any kind of nested object hierarchy (linked lists, trees, objects with references to other objects, etc)

The only other kind of indirection would be self-modifying machine code (like a Wheeler Jump). But the computing world at large has nixed that idea for a multitude of reasons

Because stuff can own other stuff and be owned at the same time. Also, arcane jackarsery.

Edit: if you want to give a function a pointer that it may change this may occur in a constructive way. I.e. replace an owned object.

Pointers just point to memory addresses, and because pointers are stored in memory addresses, it just kind of naturally falls out that way.

Pointer to pointer is fairly common stuff once you get serious with C++ but I've no idea what this abomination is supposed to even be, haha!

Because int main(int argc, char** argv)

Because pointers are real.