Welcome aboard Leland. You will be automatically subscribed to each thread that you have either started or contributed to. Those thread's titles, as they appear in the list of threads under each forum, will be highlighted in bold typeface if they contain unread replies. In addition, this icon -
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I believe you can elect to have an email automatically notifying you of new posts to your subscribed threads as well. But, aside from receiving new PMs (personal messages), I have never activated that function.