How to Build a Comment Section

A guide to the textual internet

I recently saw this tweet about the relative quality of discussions on different social sites:

And this is true! For a long time YouTube comments held a place of mockery in online discourse as the worst of the worst - both stupid and toxic. The Mississippi of comment sections, if you will. But I don’t think that’s true any longer. YouTube comment sections today are almost¹ universally filled with positive vibes and nice people. There’s been a complete turnaround. Take this explainer video by Vox on the Israel/Palestine conflict as an example. We’ve talked about how Israel/Palestine has entered a Discourse Spiral, where all conflict and all controversy on the internet starts to rotate this single mega-discourse.

Last Week in Discourse: Israel/Palestine Discourse Spirals

This is exactly the kind of comment section I’d expect to be toxic, to feature yelling and wild discourse.

And yet! See how reasonable these comments are:

I’m sure you could find some fighting in the expanded replies, but that’s positively tame. YouTube comments have come a long way.

Despite the improvement in toxicity, I do also think Marcus’s tweet above misses something important. YouTube comment sections aren’t toxic hellholes any more, but despite that they’re still not actually *good*.

(side note - I’m going to use ‘comment section’ and ‘text based posting’ and ‘discussion’ all interchangeably in this post)

The Quality vs Insanity Trade-Off

I’ve probably linked hundreds of tweets in this newsletter. I link things that are interesting, newsworthy, or notable in some way. Sometimes it’s just things that are hilarious and need to be spread. I also share tons of Reddit posts, Tumblr posts, content from Instagram and BlueSky. Sometimes even Pinterest! But I’ve never once (before this post) linked anything to do with comments on YouTube.

That’s not an accident. It’s because nothing important, creative or funny ever comes out of YouTube comments. Nobody cares about them. There’s nothing interesting happening there. YouTube lowered their toxicity, but they didn’t gain in quality.

You can imagine a four quadrant graph with toxicity on one axis and quality on another:

I think that sometimes there’s a trade-off between toxicity and quality. Twitter has always had a pretty high number of insane people, awful dog-piles, and generally toxic behavior. But it’s also where some of the most creative, funniest, and most defining parts of internet culture have developed over the last decade. I don’t think that’s a coincidence.

Is it possible to land in the bottom right quadrant? Can you have high quality posting, great conversations, and a good textual internet without a high amount of insane, poisonous discourse?

I do think it’s possible. But to figure out how, we need to talk about the specific features that make some comment sections great and others worthless.

Five Features of a Comment Section

We all know, instinctively, that some comment sections on the internet are better than others. Niche subreddits are famed for being the some of best places on the internet to talk about almost any subject. Instagram comments, in contrast, are a wasteland. The comment section of a TikTok video is literally² required to be listed as cancer-causing under California law. But why? What makes Reddit so good and interesting for conversations compared to TikTok?

There are five features that determine the nature of a comment section. Let’s talk about them, and try to think about how they impact discussion on the quality and toxicity axes.

Post Focus vs Comment Focus

When you open YouTube, the point of being there is to watch a video. The videos have comment sections, but they’re not the draw. When they envision spending an hour on YouTube, nobody at all thinks about spending that time in the comment section.

By contrast, when you think about spending an hour on Reddit or Twitter, you are very much thinking about either reading or posting text-based comments. Some sites are built around text and comments, and some are built audio or video posts. For the latter, comments are a secondary, non-critical feature. While the line is sometimes blurry,³ it’s usually pretty clear which way a site leans.

This distinction explains a lot about comment quality - it’s hard to generate meaningful discussion when comments are an afterthought. Sites built around text-based posting are simply going to have better quality. But I don’t think this factor impacts toxicity/insanity all that much. For that, we need to talk about downvotes.

Downvotes

Virtually every comment section I’m aware of on the internet has some form of upvote or like button to signal approval. But few of them have a true downvote system to signal disapproval. Reddit and YouTube are the only two major sites that I’m aware of which utilize this feature, and I think it’s a key reason why they typically have some of the least toxic comment sections.

Downvotes aren’t a tool for ensuring quality, but they are a tool for making sure people don’t have to see the very worst a comment section has to offer. Sites without them struggle because users can say awful things, get upvotes/likes from their in-group, and still find their way into the algorithm or discussion. A report function isn’t good enough to stop toxicity, downvotes are the key. Those comments might still exist at the bottom of a Reddit comment section, downvotes ensure that few people see them and that there’s a visible signal of toxicity.

Scale

Some sites are global, some are local. When you post on your personal Facebook account, it’s effectively impossible for random strangers to see it. You’re posting for a small audience of people you mostly know, and you can’t truly go viral. When you post on Twitter, anyone from anywhere in the world can theoretically see it.

Scale isn’t so much a factor of its own, but it tends to make sites MORE of what they naturally are. If a site is clever, a larger global scale will up the potential for users to run into clever content. If a site is toxic, global scale will up the potential for toxicity.

Self-Sorting

Sometimes conversation quality isn’t dictated by the technical features of the site, but by the people involved. That’s where sorting comes in. How much control do you have over creating your own crowd? Higher degrees of self-sorting can both lower toxicity and lead to higher quality discussion (but also, potentially echo chambers).

Reddit is famous for not being a single site, but a collection of thousands of disparate subreddits. Reddit has extremely high degrees of self-sorting, and on niche subreddits people can find other like minded souls and ignore or ban those who don’t fit in the community. By contrast, something like Tumblr has low self-sorting. Anyone can reblog any Tumblr post⁴ and you don’t have any control where your post spreads.

Reply-ability

How much does your comment section encourage back and forth discussion? Is the visual display built to encourage replies and counter-replies? Can people outside the initial participants easily jump in?

Sites like YouTube and TikTok have low reply-ability. There’s zero way for the comments section of one video to meaningfully interact with the comments of another video. And while replies to comments are possible, they aren’t visually distinguished or functionally very useful.

By contrast, sites like Reddit, Twitter and Tumblr all have high reply-ability. Reddit has perhaps the best nested comment display on the internet⁵ and linking to other subreddits or threads is easy. Reddit comment threads often go a dozen or more levels deep with real back-and-forth conversations. Twitter and Tumblr achieve reply-ability through retweets and reblogs - the ability to embed someone else’s comment into your own post. They also provide visual parity for replies where replies are given nearly equal visual space, size and style.

Reply-ability increases a site’s quality AND toxicity. It makes it easier to form dogpiles and mob users you don’t like, but it also turbo-charges creativity and a site’s ‘culture’ of discussion.

Factors as Vectors

The best way to understand these factors is as vectors that slide you around the 4-quadrant graph from above. For instance, the introduction of downvotes on a site will reliably reduce insane and toxic posting:

A site’s orientation towards post focus or comment focus will move them horizontally along the quality axis without impacting toxicity much:

A site’s reply-ability will impact both the potential for toxicity and the potential for creativity and quality.

The Best Comment Sections on the Internet

Based on these factors, I’m going to attempt to classify the large social media sites:

I’m not an in-depth user of every one of these sites, so I won’t claim the above chart is 100% accurate. Correct me if I’m getting something wrong! But I think this is pretty close to correct. And it gets me to this chart of quality vs toxicity.

Some of you may be surprised at how generous I’m being towards Reddit, but you shouldn’t be. Reddit’s comment quality is so strong that it’s now a common hack to add “reddit” to the end of every Google search, because it’s the only reliable way to make sure you’re getting a high-quality discussion for your topic rather than SEO-spam. It’s got huge scale, great reply-ability and it’s focused heavily on comments as a core feature.

Reddit, thanks to its pioneering use of the downvote feature, is also remarkably low on the insanity/toxicity factor for such a large comment-driven site. Horrible comments get pushed downwards and become invisible. And while there are certainly toxic subreddits, that’s a feature and not a bug. Those subreddits are largely isolated and contained (and reddit admins have become increasingly likely to ban them).

In contrast, toxic groups on Twitter and insane ideas on Tumblr spread like wildfire because of the lack of self-sorting and lack of downvotes. These sites are huge engines for creativity, clever posting, and internet culture. But they’re also insane. Tumblr is famous for being home to the weirdest parts of social justice, fandoms and generally bizarre nonsense. Twitter has almost as much insane left-leaning stuff as Tumblr while also being infested with right wing insanity. They’re places to find brilliant posts, but also places that will shove horrifying stuff in your face.

Instagram and TikTok are largely identical - the comment sections on both have relatively low impact in terms of insane toxic drama, but they also don’t matter and produce nothing important. They could, for many users, just be deleted without any real impact on the site. YouTube is broadly similar but does have perhaps a smidgen more quality and less toxicity (largely thanks to their use of the downvote).

The two most interesting cases are Facebook and Discord/Slack, which I’ll treat as the same. They’re the only two major players here that are local in scale, where the audience is likely in the hundreds or thousands rather than ‘the entire world’. That limits their ability to truly get far away from the middle of the graph. You might have a funny friend on Facebook or see a truly crazy Discord poster, but without encouragement and virality there’s only so far they can go. Facebook is generically worse than Discord in a lot of ways, but for the most part your experiences on those two sites will be more a function of your chosen community/friend group than the site itself.

That’s probably where I’ll leave this for now. If you want to build a great comment section, you basically need to emulate Reddit. There are a lot of other factors that influence a good comment section - the posting population, moderation policies, etc - but those will have to wait for a part two.

1. Obviously if you go into extremist spaces, like a communist or far-right channel, you’ll get extremist views in those comments. But I think this does apply to most everything else.

2. Figuratively

3. For instance, Elon Musk’s current attempt to pivot Twitter/X to being a ‘video first’ platform.

4. Technically you can turn off reblogs, but it’s a binary choice of ‘anyone can reblog’ and ‘nobody can reblog’ and so it’s virtually never used.

5. Particularly if you still use old.reddit.com, which you should!