From Wikipedia:
Shadow banning (also called stealth banning, ghost banning or comment ghosting[1]) is the act of blocking or partially blocking a user or their content from an online community such that it will not be readily apparent to the user that they have been banned.And from the United States Patent and Trademark Office:
By partly concealing, or making a user's contributions invisible or less prominent to other members of the service, the hope may be that in the absence of reactions to their comments, the problematic or otherwise out-of-favour user will become bored or frustrated and leave the site, and that spammers and trolls will not create new accounts.
Users of social networking system are provided with user interface elements permitting the user to post comments on pages within the social networking system. Pages may be provided for any non-user entity, including for example, pages for businesses, products, concepts, etc. Embodiments provided herein permit page moderators to ban certain content from being displayed on a page. For example, the social networking system may receive a list of proscribed content and block comments containing the proscribed content by reducing the distribution of those comments to other viewing users. However, the social networking system may display the blocked content to the commenting user such that the commenting user is not made aware that his or her comment was blocked, thereby providing fewer incentives to the commenting user to spam the page or attempt to circumvent the social networking system filters.......MUCH MORE
