Question

How do I automatically wrap default WordPress widgets into a DIV without altering the widgets themselves? I’m trying to do this, automatically:

<div class="widget">
Some WordPress widget's code
</div>

Is there a way to automatically wrap these widgets?

Answer 1

that is handled when you register the sidebar see http://codex.wordpress.org/Function_Reference/register_sidebar

and example as well

register_sidebar( array(
    'name' => __( 'Main Sidebar', 'twentyeleven' ),
    'id' => 'sidebar-1',
    'before_widget' => '<aside id="%1$s" class="widget %2$s">',
    'after_widget' => "</aside>",
    'before_title' => '<h3 class="widget-title">',
    'after_title' => '</h3>',
) );