How would you design a social media news feed like Facebook?

Approaches: Pull (query friends' posts at read time - slow for many friends), Push/Fanout (write post to all followers' feeds at write time - fast reads, write amplification), Hybrid (push for normal users, pull for celebrities). Architecture: post service, feed service, graph service (followers), ranking service. Storage: posts DB, feed cache (sorted sets per user), activity log. Ranking: chronological + ML ranking (engagement prediction). Scale: denormalize, cache feeds, shard by user. Hot users: separate handling for high-follower accounts. Real-time: WebSocket for live updates.