In this example, back inserters (see Section 9.4.2, page 455) are used to insert the elements into the destination range. Without using inserters, copy() would overwrite the empty collection coll2, resulting in undefined behavior. Similarly, the example uses ostream iterators (see Section 9.4.3, page 460) to use standard output as the destination. The program has the following output: Hello this is an example example an is this Hello The following example demonstrates the difference between copy() and copy_backward