# Viral Video Platform Algorithms

> Deep understanding of TikTok, YouTube, Instagram, and Facebook algorithms for 2025-2026. PROACTIVELY activate for: (1) Algorithm optimization, (2) Platform-specific strategy, (3) Content distribution understanding, (4) Engagement signal optimization, (5) Cold start strategies, (6) Trending and discovery, (7) Hashtag and SEO strategy, (8) Posting time optimization, (9) Cross-platform differences. Provides: Algorithm signal breakdowns, platform comparisons, optimization strategies, posting schedules, hashtag strategies, and discovery mechanisms.

- Skill: `josiahsiegel/viral-video-platform-algorithms` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds@latest add josiahsiegel/viral-video-platform-algorithms`
- Raw SKILL.md: https://api.skillmd.com/api/skills/josiahsiegel/viral-video-platform-algorithms/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Product & Planning
- Author: josiahsiegel (https://skillmd.com/u/josiahsiegel)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/josiahsiegel/viral-video-platform-algorithms

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## CRITICAL GUIDELINES

### Windows File Path Requirements

**MANDATORY: Always Use Backslashes on Windows for File Paths**

When using Edit or Write tools on Windows, you MUST use backslashes (`\`) in file paths, NOT forward slashes (`/`).

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# Platform Algorithms Deep Dive (2025-2026)

Complete guide to understanding and optimizing for TikTok, YouTube, Instagram, and Facebook algorithms.

## Algorithm Fundamentals

### How Social Algorithms Work

All major platforms use similar principles:

1. **Content Analysis**: What is the video about?
2. **User Signals**: How do viewers interact?
3. **Creator Signals**: Creator history and behavior
4. **Distribution**: Who should see this content?
5. **Feedback Loop**: Performance adjusts distribution

### Universal Algorithm Truths

**Platforms Want:**
- Users to stay on platform longer
- High engagement (interactions)
- Quality content that satisfies users
- Diverse content discovery

**What Drives Distribution:**
- Watch time (how long people watch)
- Engagement depth (comments > likes)
- Completion rates (especially for short-form)
- Sharing behavior
- Return visits

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## TikTok Algorithm (2025)

### Algorithm Signals

| Signal | Weight | Description |
|--------|--------|-------------|
| Watch Time | Highest | Total seconds watched |
| Completion Rate | Very High | % of video watched |
| Replays | High | Video watched multiple times |
| Shares | High | Direct shares to others |
| Comments | Medium-High | Written engagement |
| Follows | Medium | New followers from video |
| Likes | Lower (2025) | Heart button taps |

**2025 Update:** Shallow interactions (likes) have reduced weight compared to deeper signals like watch time and replays.

### TikTok's Cold Start System

**How New Videos Are Tested:**

1. Video published
2. Shown to 200-500 initial viewers
3. Performance measured against benchmarks
4. Strong performance = expanded distribution
5. Weak performance = limited to followers

**Cold Start Success Factors:**
- First 3 seconds retention
- Completion rate vs video length
- Early engagement velocity
- Replay rate

### TikTok Content Preferences

**Algorithm Favors:**
- Family-friendly content
- Positive emotional tone
- Educational value
- Authentic creator content
- Micro-niche targeting
- Trending sound usage

**Algorithm Deprioritizes:**
- Controversial/negative content
- Duplicated content
- Low-quality production
- Misleading thumbnails
- Watermarked content from other platforms

### Micro-Niche Prioritization

**2025 Algorithm Change:**
TikTok now heavily favors micro-niche over broad appeal.

**Benefits:**
- Specialized content sees 2.5x better distribution
- Algorithm micro-categorizes: "beginner leg workouts for women" vs just "fitness"
- Niche authority = more algorithm push for new content

**Strategy:**
- Define specific niche clearly
- Use niche-specific language and hashtags
- Build authority in one area before expanding
- Let algorithm understand your content category

### TikTok For You Page (FYP)

**How Videos Reach FYP:**

1. **Initial Test**: Small audience batch
2. **Performance Check**: Engagement metrics evaluated
3. **Expanded Test**: Larger audience if metrics strong
4. **FYP Placement**: Continued performance = broader FYP reach
5. **Ongoing**: Performance at each level determines next reach

**FYP Success Factors:**
- Hook in first 1.3 seconds
- High completion rate
- Strong replay rate
- Trending sound usage
- Relevant hashtags

### TikTok Hashtag Strategy

| Hashtag Type | Purpose | Examples |
|--------------|---------|----------|
| Broad/Trending | Reach attempt | #fyp, #viral |
| Category | Topic discovery | #fitness, #cooking |
| Niche | Targeted audience | #beginneryoga, #airfryer |
| Branded | Campaign tracking | #YourBrandChallenge |

**Optimal Strategy:**
- 3-5 hashtags per video
- Mix of niche and category
- Quality over quantity
- Trending hashtags increase engagement 23%

### TikTok Posting Schedule

| Metric | Value |
|--------|-------|
| Recommended frequency | 1-4 times daily |
| Views in first 24 hours | 68% |
| Peak window improvement | 30% better results |
| Growth with 2-4x daily | 2.5x higher follower growth |

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## YouTube Algorithm (2025)

### Long-Form Algorithm Signals

| Signal | Weight | Description |
|--------|--------|-------------|
| Watch Time | Highest | Total minutes watched |
| Audience Retention | Very High | % of video watched |
| Click-Through Rate | Very High | Clicks / Impressions |
| Session Time | High | Time viewer stays on YouTube |
| Engagement | Medium | Likes, comments, shares |
| Subscriber Actions | Medium | New subs, bell clicks |

### YouTube Shorts Algorithm

| Signal | Weight | Description |
|--------|--------|-------------|
| Watch Time | Highest | Per-video and cumulative |
| Completion Rate | Very High | Essential for short-form |
| Engagement | High | All interaction types |
| Swipe-Away Rate | High | Inverse signal (lower = better) |

**Shorts + Long-Form Connection:**
- Shorts help identify resonant audiences
- Algorithm recommends long-form to Shorts viewers
- Combined strategy = 41% faster channel growth

### YouTube Discovery Mechanism

**Where Videos Are Discovered:**

| Source | Description |
|--------|-------------|
| Home Feed | Personalized recommendations |
| Search | Keyword-based discovery |
| Suggested | After/alongside other videos |
| Browse Features | Trending, playlists |
| Notifications | Subscriber alerts |
| External | Google search, social shares |

### YouTube SEO Signals

**Ranking Factors:**

| Factor | Importance |
|--------|------------|
| Watch time | Most important |
| Click-through rate | Very important |
| Engagement | Important |
| Keywords (title, description) | Important |
| Closed captions | 94% of top videos have them |
| Video length | 8-9 minutes best for search |

**SEO Statistics:**
- 25%+ of Google searches include video snippets
- Videos can get 2-5x more views from Google ranking
- Top-ranking videos average 29 months in age

### YouTube Posting Schedule

| Day | Best Time | Notes |
|-----|-----------|-------|
| Tuesday | 6-9 PM | Peak performance |
| Wednesday | 6-9 PM | Peak performance |
| All weekdays | 12-3 PM | Good secondary window |
| Friday-Saturday | Afternoon | Broader engagement window |

### YouTube Algorithm Optimization

**Key Strategies:**

1. **Maximize Watch Time**
   - Front-load value
   - Eliminate dead time
   - Use pattern interrupts

2. **Optimize CTR**
   - Test thumbnails (up to 3 variants)
   - Compelling titles
   - Curiosity without clickbait

3. **Increase Session Time**
   - End screens with relevant videos
   - Playlist optimization
   - Content series

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## Instagram Algorithm (2025-2026)

### Instagram Reels Algorithm

| Signal | Weight | Description |
|--------|--------|-------------|
| Topic Clarity | Very High | Clear content categorization |
| Engagement | High | Saves, shares, comments, likes |
| Watch Time | High | Duration viewed |
| Follows from Reel | High | Audience growth signal |
| Audio Usage | Medium | Trending audio preference |

### December 2025 Algorithm Update

**Key Change: Topic Clarity Emphasis**

Instagram now prioritizes content that can be clearly categorized by topic.

**Impact:**
- Clear niche content gets better distribution
- Mixed-topic creators may see reduced reach
- Keyword optimization becoming more important

### The 3/8/12 Rule

Instagram's content evaluation framework:

| Time | Checkpoint | Algorithm Action |
|------|------------|------------------|
| 3 seconds | Hook evaluation | Continue or abandon |
| 8 seconds | Interest deepening | Engagement prediction |
| 12+ seconds | Value delivery | Distribution decision |

### Instagram Trial Reels

**New Feature (2025):**
Test content without risking engagement metrics.

**Benefits:**
- Risk-free experimentation
- No negative impact on feed
- Learn what works before full publish
- Test hooks, formats, topics

### Instagram Hashtag Evolution

**2025 Shift:**
Instagram moving from hashtags to keyword-based SEO.

**New Strategy:**
- Focus on keywords in caption
- Reduce hashtag quantity (3-5 vs 30)
- Posts with at least one hashtag: 12.6% more engagement
- Think "what would someone search for?"

### Instagram Posting Schedule

| Day | Best Time | Notes |
|-----|-----------|-------|
| Tuesday | 11 AM - 6 PM | Peak engagement |
| Wednesday | 11 AM - 6 PM | Peak engagement |
| Thursday | 11 AM - 6 PM | Peak engagement |

**Best Practices:**
- Consistency matters more than perfect timing
- 1-2 Reels daily recommended
- Test different times with your audience

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## Facebook Reels, Platform Comparison & Optimization Framework

Detailed Facebook Reels algorithm notes, cross-platform comparison matrix, algorithm optimization framework, and upcoming changes to watch live in `references/facebook-comparison-optimization.md`. Load that reference when comparing platform tradeoffs or adapting one asset across multiple algorithms.

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## Quick Reference

### Algorithm Success Checklist

**TikTok:**
- [ ] Hook in 1.3 seconds
- [ ] Trending or appropriate sound
- [ ] 3-5 relevant hashtags
- [ ] Clear niche focus
- [ ] High completion potential

**YouTube:**
- [ ] Compelling thumbnail (test 3 variants)
- [ ] Keyword-optimized title/description
- [ ] Strong hook (5-10 seconds)
- [ ] Closed captions included
- [ ] End screens/cards configured

**Instagram:**
- [ ] Clear topic/niche
- [ ] 3/8/12 structure
- [ ] Keyword-rich caption
- [ ] 3-5 relevant hashtags
- [ ] Sound-off friendly (captions)

**Facebook:**
- [ ] Share-worthy content
- [ ] Conversation starters
- [ ] Vertical format (9:16)
- [ ] Weekend timing considered
- [ ] Native upload (not cross-posted link)