The tiers
"Pure veg" or "Shakahari" — no meat, no eggs, no fish. "Veg" — no meat, no fish, but sometimes eggs. "Non-veg" — includes meat + fish + eggs. "Jain" — pure veg plus no onion, garlic, potato, or root vegetables.
Best regions for vegetarians
Gujarat + Rajasthan — traditionally near-100% vegetarian. Tamil Nadu + Karnataka — 70%+ vegetarian, dosa + idli + sambar dominate. Kerala + Goa + Bengal — non-veg heavy but great vegetarian options if you look.
Vegan add-ons
"Without ghee, without paneer, without curd, without milk" — the four things to say. Coconut oil replaces ghee in the south, so that's easier. Dairy-heavy dishes to avoid: any paneer, any lassi, kheer, kulfi, most Indian sweets, butter chicken sauces.
Cross-contamination
Most kitchens have separate veg + non-veg lines but not all. Ask specifically. Jain restaurants (rare but exist) are the safest bet for strictly veg.