The "tag" in this phrase comes from the children's game of tag (儿童捉人遊戲). The caught person is now "tagged" and start to catch the next victim, 可翻译成 "捉", 不过現代是 "按上标签" etc.

sorry for coming back lately,Chen. I think in these two occasions，the word “tap”is used in kind of our daily lives which means maybe we can understand it in a different way. You know，when we chat with our closest friends or family，we maybe say something more spontaneously or we will make the sentence shorter than we usaully do in formal writing，such as“thx 4 ur time”“be taken in”“an apple of love”etc. Let's go back to the sentences here. 1. "Anyone can tag you in photos and other posts.", or "If you don't like something you're tagged in, you can remove the tag or ask the person who tagged you to remove the post.".The word “tag”here，we can translate into “标biao记ji”，means same like the words“sign,mark,label”. 2. conversation between a couple about a Facebook moment. Male: I will record in my facebook: Amy means so much to me and she is the beat thing in my life. Female: make sure you tag me.The word “tag”here，we can translate into “@”（^_^）just like the time when we chat wit our friends on sociel media，we sometime“@”our friends to make them notice it. Still，we are discussing about this topics and learning together，my answer maybe not perfectly correct. I do hope the answer make sense to you.，I think that's better for us to learn with a lively and creatively mind.And maybe we can become study partners if you like.

I think when we use “tag” as a noun.，it means something like label，in Chinese we can say"标biao签qian". But in this short phrase “you tag me”，we use “tag”as a verb.When “tag” is used as a verb. ，It has the meaning of “follow” in a similar way.We say “跟gen着zhe” in Chinese. So，I think “you tag me”means “stay close to me”，and in Chinese we can say“跟gen紧jin我wo”. Meanwhile，the phrase is too short and my native language is not English，I cannot be 100% sure what I have said is correct，but I do hope words above all did some help for you.

Thanks very much! I was wondering whether there are two meanings of this word. For example, 1. "Anyone can tag you in photos and other posts.", or "If you don't like something you're tagged in, you can remove the tag or ask the person who tagged you to remove the post.". 2. conversation between a couple about a Facebook moment. Male: I will record in my facebook: Amy means so much to me and she is the beat thing in my life. Female: make sure you tag me. How to understand these two occasions? Do they mean the same as you said?

Please provide more context