Learn systems through the products engineers already recognize.

Chunking, metadata sync, version history, conflict resolution, delta transfer, and offline-first clients.

Upload pipelines, transcoding, adaptive bitrate playback, CDN placement, metadata, and watch analytics.

Idempotent payment attempts, ledgers, webhooks, retries, fraud checks, reconciliation, and money movement guarantees.

Edge enforcement, distributed counters, token buckets, hot keys, abusive traffic, and eventually consistent limits.

Preference checks, fan-out, deduplication, delivery channels, push handoff, retries, and notification fatigue.

Timeline generation, ranking, fan-out-on-write, fan-out-on-read, celebrity users, caches, and freshness pressure.

Stock reservations, oversell prevention, carts, payment windows, concurrency, compensations, and reconciliation.

Realtime collaboration, document operations, conflict handling, presence, version history, and multiplayer consistency.

High-volume writes, time-series storage, aggregation, cardinality control, query serving, and alerting latency.

Media sessions, SFUs, signaling, adaptive quality, packet loss, regional routing, and meeting reliability.

Mail ingestion, spam filtering, inbox indexing, threads, search, delivery retries, and storage at massive scale.