It is a pointer accessible only in the member functions of a struct, class or union type. It points to the object for which the member function is called. Static member functions do not have this pointer. While a nonstatic member function is called for an object, the address of the object is passed out as a hidden argument to the function. For instance, the following function call

myDate.setMonth( 3 );

may be interpreted this way:

setMonth( &myDate, 3 );

The object's address is accessible from in the member function as the pointer. This is legal, by unnecessary, to use this pointer while referring to members of the class.