The classes
AC First (1A) — private, priciest. AC 2-tier (2A) — 4-berth compartment with curtain. AC 3-tier (3A) — 6-berth, most popular. Sleeper (SL) — non-AC, budget. Chair Car (CC) — day-train seats. Executive Chair (EC) — day-train comfortable. Most tourists want 2A or 3A.
How to book
Register on irctc.co.in with your passport (you're an overseas user — the OTP goes to your international mobile). Use the IRCTC Rail Connect app once registered. Book 60-120 days ahead for peak season.
Foreign-tourist quota
IRCTC reserves seats for foreign passport holders (up to 2 per booking). Available on premium trains like Rajdhani + Shatabdi + Vande Bharat. Ask the ticket counter at a major station or use ClearTrip / Redbus. Slightly more expensive but nearly always available last-minute.
What to bring on board
A blanket-liner is worth it (blankets are provided but ugly). Ear plugs. A book. Water bottle (Vande Bharat has bottled water; older trains don't). Kindle/laptop chargers (110V outlets in AC 2A/3A).