When should I use t() in Drupal?
This page contains information about when, and when not to use the t() function in Drupal 7 (and beyond). I learned this information from the Localization API, and will add more tid-bits as I learn them. Until then, t('thanks for stopping by!');
When to use it...
When to NOT use it...
In hook_menu() and/or hook_perm()
Text declared in hook_menu() and hook_perm() are automatically translated when displayed.
Watchdog messages are stored in English, and automatically translated when displayed.
In a variable
$msg = 'Hello'; drupal_set_message($msg); watchdog('example', $msg);
In a .info file
Just use plain strings in your module's .info file, Drupal will take care of the rest.