Alerts have been activated for when you are tagged in a post, quoted, etc... We've always had them for when you get a "like", but the rest of them are now activated as well. If you want to "tag" someone, simply proceed their user name with @, as in @AtomicTommy After you type three letters, a list of users who match will pop up. Select the user you want to tag and BAM! They are tagged, and will get an alert letting them know you've done so. Just like the alerts for likes, agrees, etc.. In order to ensure this happens, you'll need to ensure your Alert Preferences are set. Hover over your alert icon (little flag in upper right corner) and select "Alert Preferences". Make sure to check those items you want alerts for, and uncheck any items you don't want alerts for. This can be seen in the below image, but if you scroll that page, you'll notice an entire page of alerts and notifications you can customize to your heart's desire.