A great product can still lose the sale at pay time. A refund that takes days can undo months of trust. And a vendor who isn’t paid on schedule will think twice before listing again. Payments aren’t a “backend detail”, they’re where revenue, loyalty, and operations meet. This guide covers core e-commerce payments and it’s use cases: checkout completion, automated refunds, vendor/seller settlements, partner commissions, on-demand gig payouts, reconciliation, and risk-aware seller onboarding. What Are…