How Does WordPress Remember Metabox Positions?

I was wondering how WordPress remembers the position of metaboxes: session basis, user basis, computer basis? Does it set a cookie? Is it saved in the database?

WordPress saves them in the databas in wp_usermeta as serilized array.
For the dashboard all are registered in meta-box-order_dashboard if the meta-box(s) are in metaboxhidden_dashboard they will not be shown. The order will be as saved in database and if not in metaboxhidden_dashboard.

Example the dashboard:

KEY: meta-box-order_dashboard

VALUE:

Array
(
   [normal] => dashboard_right_now,dashboard_recent_comments,dashboard_incoming_links,dashboard_plugins
   [side] => dashboard_quick_press,dashboard_recent_drafts,dashboard_primary,dashboard_secondary
   [column3] => 
   [column4] => 
)

There are also these meta_key(s):

• meta-box-order_dashboard
• metaboxhidden_dashboard
• meta-box-order_page
• metaboxhidden_page
• metaboxhidden_nav-menus
• meta-box-order_{custom_post}