Reddit is a social news aggregation and discussion platform where users submit content (posts) to topic-based communities called "subreddits." Other users then vote and comment on these submissions, with the most popular content rising to the top.
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The platform combines elements of a forum, social network, and content aggregator. Each subreddit functions as an independent community with its own rules, moderators, and culture. Users can subscribe to subreddits that interest them, creating a personalized home feed of content from across the platform.
Other Popular Examples: Hacker News, Stack Overflow (Q&A variant), Quora
This problem is an excellent system design interview question because it tests your ability to design voting systems, ranking algorithms, nested comment trees, and personalized feed generation at scale.
In this chapter, we will explore the high-level design of a Reddit-like platform.
Let's start by clarifying the requirements: