Working with CSV

CSV (comma-separated values) is the format every e-commerce system eventually has to read or write: product exports from a supplier, daily order dumps for accounting, review imports from a third-party platform. The csv module in the standard library handles the format's edge cases (embedded commas, quoted fields, multi-line cells) that a naive line.split(",") quietly gets wrong. This lesson covers the reader and writer pairs, the dict-based variants, dialects, quoting rules, format sniffing, and the one keyword argument (newline='') that everyone forgets.