So basically, the tag system was recently re-enabled.
That means whenever someone 'tags' you, you will get an alert.

Like above, that will appear. Now, if you don't know how to do this, I'll show you.
If you want to be fancy, you can type the whole code, which is something like ewww
But the simple way is to just do @ then someones name.
So if I did @jarroyonaples, it will come up in his alerts as like the picture above.
Of course, when you edit something, you will get to see the whole bb code. The @ is just like a bbcode filler, so you can edit the name, and the person who you originally tagged.
Also, when you start typing after the '@', you will get a list of all people with that name.

If you would like to turn them off, go to "Alert Preferences" in settings, and check off this:

The tag you in a message thingy.

EXAMPLES:
@CypriotMerks
@Noobcrew
Note:
Please do not spam tag moderators/other people, it is very annoying and will not be tolerated. We're busy, and will handle whatever you need handled in due time. Thank you.