When you add the np subdomain prefix to a reddit domain, it links to a non-participation version of the page. The idea is that it helps to reduce "brigading",

When you add the np subdomain prefix to a reddit domain, it links to a non-participation version of the page. The idea is that it helps to reduce "brigading", as in if a thread is linked to by an external party or another subreddit, the thread is not so easily derailed from its original context and audience. Of course if you actually want to participate in the thread, its not difficult to simply remove the prefix. But it might make some people think twice. NP links are mainly used by inter-subreddit references, as "brigading" is against the reddit rules, and can result in a subreddit being banned. I can see why it all seems a bit ridiculous.