AIM is different from other clients such as Yahoo Messenger in that it does not require approval from one buddy to be added to another's buddy list. As a result, it is possible for users to keep other unsuspecting users on their buddy list to see when they are online, read their status and away messages, and read their profiles. However, one can block another user from communicating and seeing one's status; though this does not prevent the user from creating a new account that is not blocked and therefore can still track the first user's status.
