Alerts are notifications you get on the site due to your interactions with content or from forums and posts you have opted to watch.
Your Alerts can be found in the upper right of the site (the bell icon).
You can adjust your Alert Preferences at anytime in your preferences. Alerts eventually expire, so you’ll miss them if you don’t log in for a while
If you have chosen to Watch forums or Watch threads you will receive an alert when new content is posted to those. Unless you have switched this off in your preferences, you are automatically watching any thread you start or reply to.