Every French town has a marché — most have several, each on a different day. Find the next open market, what it sells, and which ones are worth a special trip.
Most visitors either skip markets (because they don't know which day) or get unlucky (arrive on the wrong day). Markets rotate by weekday; some are daily, some are weekly, some are twice-weekly (different foci each day).
The trick locals know: market day is part of town identity. Saturday is the "big" market day in most French towns. Some are specialty (flower-only, organic-only, antiques-only). Knowing this lets you plan a trip around it.
The next market day for that specific city, with hours, location, and what it's known for.
Specific things this market is known for that aren't always on offer at supermarkets — local cheese, regional saucisson, fresh herbs.
Markets have unwritten rules: bring cash (many stalls don't take cards), touch nothing until asked, accept that "tourist tax" sometimes applies.
Politeness basics: "Bonjour", "S'il vous plaît", "Merci." Beyond that, pointing works. Numbers for prices you can read. Vendors will appreciate attempts.
Larger stalls take cards; many small producers don't. Bring €20–€50 in cash. ATMs are usually near market grounds.
In tourist-heavy areas, vendors raise prices and stock "for tourists" (junk). Local-producer markets (like Raspail Paris bio, L'Isle-sur-la-Sorgue Sunday) keep quality higher. Look for "Producteurs" signs.