Buddy List provides you with a way to keep track of your friends.
If there are users whom you want to follow and make sure you don't miss their topics, then add them to your buddy list.
After that, you can filter topics in Newest Topics and Active Topics lists to just your buddies, so that their topics don't get lost among others.
Additionally, topics from your buddies are marked as "(buddy)" in the digest, so it's easier to spot.
Also, when viewing your buddy list, you can see which of your buddies are currently on the forum, marked as "(online)".
To add a user to your buddy list, go to that user's profile page and click "Add To Buddy List" link.
The link for the buddy list is available under My Profile. You can manage your existing buddies on that page.
From that page, you can also view Newest Topics and Active Topics by your buddies, as explained above, links at the top of the buddy list.
You can also store notes about each user in your buddy list. So if you need to save another person's contact information or other details for quick retrieval later, you can use the "notes" text field.
Your buddy list is private. Other users can't see who is in your buddy list. Not even those you add as buddies.