What is the significance of caddr_t and when is it used?

Question

Can somebody please tell me:

1. What is caddr_t ?
2. When is it used ?
3. How it is different from void* ?
4. When to

Answer 1

caddr_t was used as a pointer to a core address. I used it in SVR4 when I needed to access kernel structures from user space (having used mmap to access /dev/kmem). Even when "/proc" existed, the ps command still used mmap of the kernel to start walking the process table. As everybody states it was superseded by void *.