A common idiom is to suffix the type with _p to indicate that it's a pointer while still retaining the pointery qualities.
Sometimes it is necessary to use only the pointer type if the struct that it is pointing to is not publicly available. This helps facilitate data hiding. I.e.
typedef struct hidden_secret_object * object;
void change_object(object foo);
this allows you to change the way that hidden_secret_object is structured without breaking external code.
