FBA is the engine behind Amazon's 1-day and 2-day delivery. Sellers send inventory to FBA fulfillment centers (FCs); Amazon stores it, picks/packs orders, ships to customers, handles returns, manages customer service.
For Indian D2C brands: FBA opens up Amazon Prime eligibility (the Buy Box dominantly goes to Prime + FBA listings), reduces shipping cost (Amazon's negotiated rates), but charges fulfillment fees (₹40-150/order based on size) + storage fees (per cubic foot per month).
Alternative: Easy Ship (FBA Lite) where seller stores inventory but Amazon picks up + delivers. Cheaper than FBA but no Prime eligibility.