Lesson 2 of 13
The checkout flow.
What the shopper sees, and which services the platform calls from the cart to the order confirmation.
By Nagesh Koritala 4 min read Last verified: November 2026
- Lesson 1: Improve the checkout
- Lesson 2: The checkout flow (this lesson)
- Lesson 3: Authorization
- Lesson 4: Payment states
- Lesson 5: Capture
- Lesson 6: Clearing and settlement
- Lesson 7: Cash capture
- Lesson 8: Returns and refunds
- Lesson 9: Disputes
- Lesson 10: Tokens and stored credentials
- Lesson 11: Transaction types
- Lesson 12: Complete reference
- Lesson 13: Payments compliance
The shopper sees a few screens. Behind them, the commerce platform calls several services in order. Each call answers one question: Where is it going? What does it cost to get there? What tax applies? Is this person who they say they are? Can they pay?
Watch step 5 closely. The card number goes from the shopper's browser straight to the payment provider. Your servers only ever see a token that stands in for the card.
Order varies by platform. Some check inventory when the item enters the cart, some only at order placement. The principle holds: price, tax, and stock are all re-confirmed before you ask the bank for money.
Sources for this guide
Card network rules change. Time limits, fees, and authorization windows here reflect published rules and provider documentation as of late 2026; confirm details with your processor before you build against them.
Sources
- Visa authorization and clearing time frame changes, April 2024 (TD Bank summary)
- Checkout.com: Visa authorization processing time frames
- Stripe: Place a hold on a payment method
- Revolut: Clearing windows by card brand
- Moov: Card-not-present best practices
- Adyen: Dispute timeframes
- Cybersource: Stored credential framework (CIT, MIT, standing instructions)
- VGS: DPAN vs MPAN
- Stripe: Apple Pay merchant tokens
- Google Pay: Payment data cryptography (PAN_ONLY and CRYPTOGRAM_3DS)
- Checkout.com: Google Pay authentication methods and liability shift
- Solidgate: Why the Apple Pay card number differs from the card
- Spreedly: Payment Account Reference (PAR)
- Visa: Authorization and reversal processing best practices
- Visa: Authorization framework time frames (2024)
- Visa: Declined transaction resubmission rules
- Visa: Dispute management guidelines for merchants
- Visa: VAMP fact sheet
- Visa: Account Updater FAQ
- Mastercard: Chargeback Guide, Merchant Edition
- Mastercard AN 5524: CIT and MIT indicators (via AIB Merchant Services)
- Mastercard Gateway: Cardholder and merchant initiated payments
- Adyen: Mastercard Transaction Link Identifier
- American Express: US Disputes Reference Guide
- American Express: International Merchant Regulations
- Adyen: Adjust authorisation (validity by brand)
- Apple: Merchant tokens (MPANs)
- Apple: Payment token format reference
- Apple: Merchant Token Notification Services
- Google Pay: Merchant-initiated transactions
- Google Pay: Token lifecycle management
- Stripe: PaymentIntent lifecycle
- Stripe: Refund object
- Stripe: Dispute object
- Stripe: Subscription object
- Stripe: Decline codes
- PCI SSC: Future-dated requirements of PCI DSS v4.x
- Report URI: SAQ A changes in PCI DSS 4.0.1
- SecureTrust: PCI DSS SAQ types
- Chargeback Gurus: Regulation II and card-not-present debit
- Baymard Institute: Cart abandonment rate statistics (updated September 2025)
- Baymard Institute: The current state of checkout UX (2025)
- Baymard Institute: Checkout optimization and average form fields (2024)
- Baymard Institute: Inline form validation
- Baymard Institute: Adaptive validation error messages
- Adobe: 2025 US holiday shopping season
- US Department of Justice: Guidance on web accessibility and the ADA
- W3C: Web Content Accessibility Guidelines (WCAG) 2.2
- Apple: Human Interface Guidelines, accessibility
- Stripe: How to increase checkout conversion
- Stripe: The checkout process, reducing friction
Your progress stays on this device.
Next: Lesson 3
Authorization.
The round trip from merchant to issuer, what an approval really means, and how long a hold lasts.
Questions about payments? Email me. I read every note.