These two tags have been added to give you more options when posting. Feel free to use them as you see fit.
If there are any problems let us know on the Site Issues and Feedback board.
Spoiler tags have been around forever so not much to explain. By default they collapse their contents hiding them so that the user has to click a button in order to view their content.
Since many of our boards will allow not safe for work content I've included a second spoiler tag specifically to identify NSFW content. You won't need it everywhere but it'll be a nice option and may even be required on some boards.