Inside the Algorithm
What three categories of signals does TikTok list as influencing its “For You” feed?
User interactions, content information, and user information.
Good feed design is about triangulation, combining behavioral signals (like engagement), content metadata, and user traits. When those work together, we can start to infer intent rather than just interest.
What is the maximum number of photos or videos you can include in an Instagram carousel post?
20; This increased limit (from 10) was introduced to allow users to share more content in a single post and is now available globally.
Carousel formats show that interaction depth can matter more than feed time. Multi-frame posts invite swiping, increase dwell time, and reward creators who tell stories, proving that “micro-engagement loops” are just as powerful as scrolling itself.
In early 2024, Meta became the first major social company to automatically label AI-generated images across Facebook and Instagram. What phrase appears on those posts?
“Made with AI.”
Transparency in feeds is becoming part of the product experience itself. As generative content floods platforms, credibility markers like provenance tags and AI labels could be critical for preserving trust and user confidence.
True or False: Instagram treats “saves” as a stronger ranking signal than likes.
True — according to IG, “saving” indicates deeper content value and intent to revisit.
Saves” reveal genuine content value, not just momentary approval. The strongest engagement signal is often what people intend to revisit, not what they tap impulsively.
The heart “Like” button on X (Twitter) was originally what shape?
A star — called a “Favorite.”
What kinds of signals help Instagram find “compelling content from a wide array of sources”?
Popularity signals (follower count, engagement) in addition to the relationship and interest signals.
Recommendation systems reward posts that appeal to both social and content-based relevance. Balancing familiarity (who you follow) and discovery (who you don’t) keeps feeds feeling both safe and surprising.
Which platform was first to popularize infinite scroll with an auto-refreshing feed rather than page-based navigation?
Facebook — originally implemented continuous scroll in 2011, later adopted widely.
Infinite scroll changed how people experience time online, replacing completion with continuous curiosity. It turned feeds into flows, where every interaction produces more context, but also more cognitive load. Modern feed design must balance frictionless exploration with the need for psychological closure.
Which social app introduced a Following feed alongside algorithmic recommendations shortly after launching, due to public response?
Threads.
Even “algorithmic-first” apps end up giving users control levers. The tension between personalization and predictability defines every feed; too much automation erodes agency, too little kills discovery.
True or False: TikTok’s algorithm considers whether a user shared a video privately over DM as a stronger signal than commenting publicly.
True — private shares indicate higher perceived value and virality potential.
What people share privately often says more about what’s truly viral than public comments ever could. TikTok is leaning into that insight, treating behind-the-scenes sharing as a stronger signal of cultural relevance than surface-level engagement.
In late 2024, YouTube introduced an experimental feature called [blank] inside its app. What was the name, and what new type of content does it add to the feed?
Playables; lightweight, playable casual games integrated directly into YouTube.
YouTube’s experiment shows how platforms are broadening what “feed content” can be. By blending passive consumption (video) with light interactivity (games), they’re testing new ways to increase session depth and reduce fatigue.
On TikTok, which type of signal is generally weighted more heavily in ranking: user interactions, content info, or user info?
User interactions (include the time spent watching a video)
Not all engagement is equal — watch time and replays are stronger predictors of value than likes or follows. Platforms that study how people engage understand satisfaction far better than those that only count actions.
Instagram found that people are about X% more likely to tap “Show fewer posts like this” on suggested posts (from the algorithm) than on posts from people they follow.
What %? (Answers +/- 10% will be accepted!)
50%.
People trust posts from people they follow more than algorithmic suggestions. They’re more likely to reject suggested content because it feels less relevant or harder to understand why it’s being shown. That’s why building trust in recommendations is as important as showing the right content.
Which social platform is now testing a short-form video-first feed in India?
Instagram.
Instagram isn’t afraid to double down on where user time already goes. With most engagement now coming from video on IG, they are testing what happens when the entire feed aligns to that behavior. It’s a reminder that they move fast to validate big shifts rather than wait for certainty.
True or False: TikTok’s recommendation system treats a 100% completed watch as more valuable than a like.
True — completion rate is one of TikTok’s most heavily weighted signals.
Depth of attention is a more reliable success metric than frequency of interaction. The best content doesn’t just capture clicks but it sustains focus.
Which major platform said they are thinking through a vision for their feed that is "agentic" - where users can just prompt the Feed to tell them what to show?
X.
The future of personalization could be 100% conversational. Moving from “recommend me” to “show me” redefines algorithmic control as a co-pilot, not a black box.
In 2025, Meta’s feed ranking began factoring in a new metric around comments. What was it?
Time to comment. Early engagement predicts long-term post vitality — the faster comments arrive, the higher it’s boosted.
Early engagement velocity is a proxy for resonance. Detecting and amplifying posts that quickly spark discussion can make feeds feel more “alive” in real time.
TikTok officially says it will not show two videos in a row using what, even if you like them both?
The same sound. It avoids back-to-back videos with identical audio to keep the feed fresh.
Diversity of stimuli sustains curiosity. Even tiny variations — sound, creator, format — prevent repetition fatigue and keep users in a discovery mindset.
Which platform allows users to “pin” custom feeds as alternative feeds next to their home feed tabs? What is the feature called?
X; Lists.
Multi-feed experiences like Lists often cater to vocal power users who want more control and curation. Platforms experiment with them to signal transparency and flexibility, but most engagement still happens in the main, algorithmic feed.
In 2023, TikTok quietly tested a new photo-only feed. During the first month, what unexpected engagement metric did photo posts outperform videos on?
Photo carousel saves — users saved image posts 3x more than video posts.
“Saveable” content drives a different kind of engagement loop. Great feeds balance inspiration (save) and stimulation (watch).
The average person scrolls roughly how many meters per day on social media?
8,000 meters (8 km)
YouTube’s internal ML team has shared that the recommendation system now trains on both [blank] and [blank] equally to measure “emotional resonance.”
What are the signals, and what’s the goal?
Likes & dislikes. Both positive and negative emotional reactions indicate high engagement, because people who feel something (even anger or disagreement) are more likely to watch longer, comment, and keep coming back.
YouTube’s algorithm doesn’t distinguish between positive and negative emotional engagement — it values intensity of reaction because that’s what keeps users watching. The risk is that optimizing for emotional engagement can promote divisive or sensational content if not carefully managed.
Meta killed its Facebook “[Blank] Tab” in the U.S. and U.K. in 2024. What was it, and why?
News. Meta said users “didn’t come to Facebook for news”; only 3% of feed time was spent on it.
The sunset shows that feeds follow user behavior, not company ambition. Even massive platforms can’t force habits that don’t feel natural. People open feeds for connection, not obligation. If content doesn’t create ongoing value, users won't care.
Which platform rolled out customizable, shareable topic feeds in 2025 to encourage community curation?
Threads.
Platforms are realizing that algorithms alone can’t define taste, but communities can. By making topic feeds both customizable and shareable, Threads is experimenting with a hybrid model where discovery is powered as much by social curation as by machine learning.
According to internal Meta studies, adding a half-second delay before showing the next Reels clip increased average watch time by how much?
(Will accept answers within +/- 2%)
Roughly 3–5%, because the short pause reduced cognitive fatigue and made users feel more in control.
Perfect speed isn’t always optimal speed. Introducing small moments of pause helps users feel agency, reduces fatigue, and ultimately keeps them scrolling longer.
When TikTok’s first launched “Repost” in 2023 they made one interesting design/UX choice, that they later changed. What was it?
Reposts initially didn't show up on your profile; they only surfaced to followers in their feeds. They have since launched a repost tab on profiles.
Reposts without profile clutter make social endorsement invisible but viral. It’s a tension between self-presentation and influence. People spread content without owning it.