Q. In what format should I store data in S3, and how do I partition it?

 A:
Choose a format based on your downstream needs (CSV, JSON, Parquet, Avro). Parquet is efficient for analytics. Partition data by date (e.g., year=2025/month=09/day=24/…) for fast retrieval. Use robust naming conventions, avoid overly nested paths, and be consistent.