Author
Payment systems expert and technology executive
Arif Ünal is a technology executive with more than 20 years of experience in banking, fintech and payment systems. He writes about card payments (issuing and acquiring), POS, ATM, e-money, FAST and Turkish payments regulation (BRSA and CBRT). He has held senior roles at Finagotech and managed payment systems and digital banking teams at Emlak Katılım, Vakıf Katılım and Türkiye Finans. He holds a B.Sc. in Industrial Engineering from Istanbul University and an M.Sc. in Management Information Systems from Marmara University.
976 articles
Laws & Regulations
The Visa Core Rules and Visa Product and Service Rules documents define the fundamental rules that apply to all institutions in the Visa network. They are updated regularly, and all members are expected to follow the latest version.
Payment Systems
How do banks fund so many points, bonuses, and discounts? This post explains the credit card profitability model: merchant commissions, interchange, interest income, installments, and why campaigns are an investment in transaction volume rather than a cost.
Open Banking
Embedded Finance means integrating financial products and services into non-financial platforms, experiences or business processes. In other words, services offered by financial institutions become part of the product or service flows of non-financial organizations.
Payment Systems
Every payment transaction completes in seconds, yet dozens of controls run behind the scenes. This post covers the precautions for authorization and clearing, the critical role of reversals, and the financial loss scenarios most often seen in the field.
Merchant & POS
Visa's Merchant Data Standards Manual covers classification, identification and data standard requirements for merchants, payment facilitators and marketplaces, including merchant naming, location and MCC rules. Here is what it contains and where to find it.
Merchant & POS
In payment systems, every exchange between POS devices and bank or payment institution systems runs on a specific messaging standard, generally based on ISO 8583. However, each country, bank, or switch network defines its own version of this standard.
Merchant & POS
In EMV-based debit card transactions, PIN verification is decisive for both security and liability. What happens when a card that only supports online PIN is sent to the issuer without a PIN, and the issuer approves it? Who owns the risk?
Merchant & POS
Partial authorization lets an issuer approve part of the requested amount when the card lacks the full balance, with the rest paid another way. This post covers the technical, receipt, clearing, reconciliation, merchant and certification requirements for acquirers.
Merchant & POS
Partial Authorization lets an issuer approve part of a transaction instead of declining it when the balance or limit is insufficient. This post covers how it works in ISO 8583, whether it is mandatory, and why it matters for the business.
Online & Authorization
OpenAI and Stripe announced the Agentic Commerce Protocol (ACP), with Instant Checkout live on Etsy and Shopify in the US. What this means for payment facilitators and e-commerce platforms, and what may come beyond one-click checkout.
Credit Card
Yes. A certificate must be generated for every new BIN and loaded onto the card chip, establishing secure communication between the chip and the terminal. This is especially critical for verification in offline transactions.
Merchant & POS
In EMV transactions, Application Selection is the process of choosing among the applications supported by both the card and the terminal. It is the first stage of authorization, so it is very important. This post covers the PSE and List of AIDs methods.