AddressOf

Most of the time you will not need to obtain any low level information about your variables.
However there are a few Windows API functions that require the memory address of a variable.

link - learn.microsoft.com/en-us/office/vba/language/reference/user-interface-help/addressof-operator 

When you want to use API functions the following functions will prove useful:
VarPtr - returns the address of a variable
VarPtrArray - returns the address of an array
VarPtrStringArray - returns the address of an array string
StrPtr - returns the address of the UNICODE string buffer
ObjPtr - returns the pointer to the interface referenced by an object variable