Affirm is a financial technology company offering "Buy Now, Pay Later" (BNPL) installment loans for online and in-store purchases, letting shoppers split costs into fixed monthly payments, often with 0% interest options or rates up to 36% APR, providing transparency with no hidden fees or late fees, and allowing users to pay over time without a credit card. It acts as a point-of-sale lender, giving real-time loan decisions and helping build credit with on-time payments, functioning as a short-term loan rather than revolving credit.