TikTok System Design interview questions focus on building massively scalable, low-latency media systems with strong personalization. Expect prompts that center on the For You Page, video storage and delivery, real-time engagement (comments, likes, live), and content moderation. Interviewers evaluate how you clarify requirements, balance trade-offs (latency vs. personalization, consistency vs. availability), choose data models and APIs, and plan for capacity, caching, replication, monitoring, and failure recovery. Typical sessions run 45–90 minutes on a whiteboard or virtual board and alternate between high-level architecture, capacity estimates, and deep dives into one or two components. For effective interview preparation, practice a consistent design template: ask clarifying questions, estimate scale, propose a high-level architecture, and drill into bottlenecks and trade-offs while noting operational concerns. Work problems that include CDNs, streaming pipelines, caching, sharding, and ML-driven ranking, and rehearse explaining choices succinctly. Do timed mock interviews, prepare back-of-the-envelope calculations, and be ready to suggest optimizations and mitigation strategies for common pitfalls.