@huige I do not think you can tag posts for now... just topics... please check some relevant discussions on the topic below...
Link Preview Image Tags for posts in addition to topicsOver at mangolass.it (managed by @scottalanmiller) we have long had problems with search just completely sucking. Has anyone ever looked into the feasibility...
faviconNodeBB Community (community.nodebb.org)
hopefully in the near future though š