A user with a Verve card from FintechA swipes ₦10,000 at a merchant whose payment processor is FintechB. FintechA is the ISSUER (the card belongs to them). FintechB is the ACQUIRER (the merchant is their customer). One swipe; two completely different ledger flows. The issuer charges the user, pays the acquirer through the scheme. The acquirer collects from the scheme, pays the merchant after deducting fees. This lesson posts BOTH sides of the same ₦10,000 transaction so you can see the symmetry, and why a single fintech that does both (a Stripe, a Paystack) has to keep its issuer ledger strictly walled off from its acquirer ledger.