Tags are a common method of adding keywords to content to aid searching and discovery. In our community, we're adding support for applying tags to threads, as well as a framework for add-ons to add tags to their own content types. Thread tags apply to the thread itself (rather than individual posts). As per below image, you can see there is an option to tag the keywords as Tags: seperated by commas for each keywords. Tags are displayed at the top of the thread view, independent of any post.