Three general points:
a) Red icons are unread items
b) Blue/grey are read
c) A star on any topic means you have posted in it

- Announcement
- Sticky topic
- Read topic
- Unread topic
- Read topic that you have posted in
- Unread topic that you have posted in
- Hot topic
- Locked topic
- Moved topic
- Forum with subforums (which have been read)
- Forum with subforums (which are unread)
- Link forum

- Attachment
- Go to last post in the topic
- Go to last unread post in the topic
- Subforum read
- Subforum unread