A userbox is a small colored box that allows users to add small messages on their user pages. It is an extension of the babel boxes used for users' language abilities. The Wikimedia Commons has a large range of icons for use within boxes.
The primary purpose of user boxes and user categories should be to alert other Wikipedians to ways you might aid them in editing. For instance, if you speak a second language or have professional expertise in a technical field, other users will know they can contact you for assistance.
Common uses for boxes include user interests, user skills, technical information, Wikipedia activities, or mere fun.
There has been controversy over the use of userbox templates for controversial or unencyclopedic userbox content. The German Solution to the userbox controversy is to move userboxes out of template space, and into userspace. When the user subpage is transcluded without substitution by multiple other users, it is considered a 'template'. In all cases userboxes must not be personal attacks, hate boxes, unfair use or copyrighted images. Obey WP:USER, WP:CIVIL, and WP:NPA.
