High-Level Design
Design a photo-sharing service: users upload images, follow other users, and see a timeline of recent posts from the people they follow. It must ingest a high write volume of large binary objects, serve images at low latency worldwide, and assemble personalized feeds at scale.
In scope: uploading a photo with a caption and location so it becomes visible to followers, viewing a timeline of followed accounts, viewing a profile's grid of posts, and following or unfollowing. Comments, likes, direct messages, and search are out of scope.
What a strong answer sounds like
State the decision, connect it to a requirement, and name the tradeoff. Keep the design focused on the workload in the prompt.
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