Purpose for name tags in facebook?

[Paetur A R. J.]

I am not trying/attempting to sound stupid or troller, but a curiosity just came before me.

In some facebook comments, likely about a subject or a video, people simply "tags" his/her names, when they comment. And here is my todays question to you: Why? When it involves with a video, commercial, celebration and ect., some people's comments contains just tags of the person's name.

Unfortunately, I don't have the photos to provide a proving material of what I am trying to tell, so I'll cross fingers that you still understand what I am trying to talk about.

I'm still new to this "facebook" stuffs, so please help me out.

I would appreciate your constructive and helpful ways to explain this.

Thank you for reading my message and I'll look forward for some nice answers

PS: And I know facebook isn't the only place for taggings. Don't get me wrong.
Edit: - to sound stupid or trolling, -
PSS: Pardon for my gramma.