Difference between retain and copy?

Question

What exactly is the difference between retain and copy? what is its significance on reference counting?

I know that when an object is allocated using alloc/retain, reference count goes up by one. so how about using copy?

Another question relating to this is, the difference between using
@property(nonatomic, retain) and @property(nonatomic,copy)?

Answer 1

retain -- is done on the created object, it just increase the reference count.

copy -- create a new object