national, religious, regional. planning your next long weekend.
national — all-india public holiday (gazetted) religious — hindu, muslim, christian, sikh, jain, buddhist festivals regional — new years, harvests, local festivals observance — international days, birth anniversaries
Dates for lunar / tithi-based festivals are best estimates — moon-sighting can shift Eid by a day. Consult your state's holiday notification for official sector-wide holidays.