Gun Deals, Beer Trade and Cigar Market are three of the latest communities to be banned by Reddit in a move to distance the social website from transactions of "illicit or strictly controlled" goods.
Drugs, personal information and "paid services involving physical sexual contact" are also on the list of banned transactions announced on Thursday.
A Reddit spokesperson said "users who attempt to conduct [these transactions] will be banned from the site", but declined to answer all of the BBC's questions about the bans.
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How many people have been affected?
One user put together a list of 38 communities, or subreddits, which had been banned since the announcement. They estimate that more than 50 were removed in total.
Of this list, 12 subreddits relate to firearms. For example, the r/gundeals subreddit had 122,311 subscribers as of 27 January 2018, according to the Wayback Machine digital archive.
The cumulative subscribers of only five other banned communities suggest that at least 250,000 people have been affected.
Why have these specific subreddits been targeted?
A Reddit spokesperson clarified that "transactions that are either illicit or strictly controlled" are now prohibited.
While the sale of firearms is not illegal in the United States, it is heavily regulated. A Reddit representative explained that "there are very specific conditions necessary to make their sale legal" and added that the website "is simply not set up to ensure that those legal conditions are being met".
But this stance has caused consternation with users of the Gun Deals subreddit, who explain that their community was not involved in the sale of guns other than providing links to legal retailers.
And as one Twitter user pointed out, the ban extended to a subreddit dedicated to the exchange of bullet casings, rather than live ammunition.
Didn't YouTube recently ban videos linked to firearms?
This week YouTube took the decision to ban videos that show people how to manufacture or modify guns and their accessories.
One person, who deleted their account after commenting, accused Reddit of banning all gun-related subreddits "like YouTube is doing with firearm channels right now".
Reddit has been accused of "agitating the problem" by banning these communities, while another called it a decision based on "advertiser-friendly censorship".
Out of a list of 38 banned communities, 12 concerned gun-related sales or trades.
What does this mean for Reddit Secret Santa?
Some Redditors have pointed out that the new rules appear to contradict with the site's annual Secret Santa tradition, as gift-givers are required to exchange personal information in order to send their gift.
Users were quick to point out the inconsistency, with one asking how Reddit will ensure people do not gift banned goods, with another suggesting that "there's no way to know if alcohol or tobacco products are sent".
It is unknown what implications the new rules would have for their gift exchange programmes, specifically Secret Santa.