What are subscribed threds? And how do you subscribe to them?

Subscribed threads are those that you have email a daily digest or a instant notification or a reply....

you can subscribe to all by an option in the User CP under user options..

or individually when replying by clicking subscribe to this thread..

Another way is under thread tools tab in every thread.. there is a spot to click to subscribe.... It is handy to know if someone has replied to your own.. or had more info on a similar subject in a thread you found.

hope this helps.