tags like field that can be add by anyone

I'm wondering if anyone can make the tag field that the tags (or something like it) can be add and subtract by anyone or registered people at anytime (like after the article is published, ppl can add and subtract the tags from the article.) sound wierd?


how about some fields where people can interact with after the article is published? like add and remove or edit without exactly changing other parts of the article and it would only affect that field.