How do I tell which topics are new and which have been read?

When viewing the $2, new (unread) forums are indicated by the following symbol:
- forum_unread.png (4.52 KiB) Viewed 5763 times
Any forum with this symbol next to it indicates that forum contains content that you have not viewed before. If you have already viewed all the content in a particular forum, the following symbol will be displayed next to it:
- forum_read.png (3.69 KiB) Viewed 5763 times