global $post and get_posts( )

Hi,
I’m just curious about something that maybe has a obvious answer but I cannot find it.

Why do you use global $post; with get_posts( );, like in the example bellow. Is it mandatory?

<?php
global $post;
$args = array( 'numberposts' => 5, 'offset'=> 1, 'category' => 1 );
$myposts = get_posts( $args );
foreach( $myposts as $post ) :	setup_postdata($post); ?>
	<li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
<?php endforeach; ?>

Thank you,
Sacher