Design Twitter
Design a system like Twitter, a social media platform that allows users to post short messages, follow other users, and view a timeline of posts from users they follow.
Typeahead Suggestion / Autocomplete Design
Design a typeahead (autocomplete) service that returns the top-3 suggestions for the prefix the user is typing. Suggestions should be ordered by a combination of popularity (frequency) and recency. The system must provide real-time responses with very low latency, scale to large traffic, and be highly available.