File Formats at a Glance CSV name,age,city Alice,25,NYC Bob,30,LA ✓ Human-readable ✓ Universal support ✓ Spreadsheet-friendly ✗ All values are strings ✗ No nested data ✗ Large file size Best for: small data, sharing JSON {"name": "Alice", "age": 25, "addr": {"city":..}} ✓ Preserves types ✓ Nested structures ✓ API standard ✗ No date type ✗ Large file size ✗ Slow for analytics Best for: APIs, config files Parquet col1 col2 col3 ✓ Full schema + types ✓ Small (compressed) ✓ Fast column reads ✗ Not human-readable ✗ Needs pyarrow lib ✗ Bad for single rows Best for: analytics, big data