Name some of the global variables in drupal?

$custom_theme;

Change active default themes

$base_path;

Tell the cuurent base path

$base_url;

Tell the site url

$db_type;

Tells active Database type

$theme_path;

Tells the current theme path

$language;

Tells the active language

$user;

List has obj of user details

These are most often used global variable in drupal.