Nagesh Koritala

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Field guide

Anatomy of a Checkout.

For anyone who wants to become a product manager for payments and checkout: here is what I’ve learned, put together in one place. When a shopper taps “Place order,” no money moves. What follows is a chain of promises, requests, and ledger entries across several companies, and this guide walks you through it one diagram at a time.

  • 13 lessons
  • About 2 hours of reading
  • Free, no sign-up
Start Lesson 1: Improve the checkout

By Nagesh Koritala Last verified: November 2026 Your progress stays on this device.

The guide as one picture: four parts. Checkout, lessons 1 and 2; The money, lessons 3 to 7; After the sale, lessons 8 and 9; Deep dives, lessons 10 to 13. Arrows lead from one part to the next, and lesson 1 is marked in red: start here. Checkout12The money34567After the sale89Deep dives10111213 start at 1, follow the money

What you’ll learn

By the end, you’ll be able to:

  • Find what makes shoppers leave a checkout, fix each part of it, and measure whether a fix helped.
  • Explain what happens after “Place order”: authorization, capture, clearing, and settlement, and when money actually moves.
  • Choose between a void, a reversal, and a refund, and know what evidence wins a dispute.
  • Tell an FPAN from a DPAN, an MPAN, and a network token, and label any card payment by channel, initiator, and credential.
  • Know which PCI DSS questionnaire fits a checkout, and which US rules and laws apply to it.

The path

Thirteen lessons, in four parts.

Start at lesson 1 and follow the money, or jump to what you need this week. Each lesson has a diagram to step through.

Part 1

The checkout

What the shopper sees, and what to fix first.

  1. Lesson 1: Improve the checkout

    Why US shoppers abandon checkout, what to fix in each part of it, and how to measure whether a fix helped.

    11 minutes

  2. Lesson 2: The checkout flow

    What the shopper sees, and which services the platform calls from the cart to the order confirmation.

    4 minutes

Part 2

Follow the money

From the first hold to money in the bank.

  1. Lesson 3: Authorization

    The round trip from merchant to issuer, what an approval really means, and how long a hold lasts.

    4 minutes

  2. Lesson 4: Payment states

    The life of a payment as a state machine: created, authorized, captured, settled, refunded, and disputed.

    4 minutes

  3. Lesson 5: Capture

    Charging when goods ship: split shipments, partial captures, and reauthorization when a hold expires.

    4 minutes

  4. Lesson 6: Clearing and settlement

    When money actually moves between banks, and the layers of fees inside every card sale.

    7 minutes

  5. Lesson 7: Cash capture

    How finance proves every order was paid: matching deposits to orders, and working the exceptions.

    4 minutes

Part 3

After the sale

Returns, refunds, and chargebacks.

  1. Lesson 8: Returns and refunds

    The return workflow, and how to choose between a void, a reversal, and a refund.

    6 minutes

  2. Lesson 9: Disputes

    The chargeback lifecycle, the uneven clocks, and the checkout evidence that wins a dispute.

    4 minutes

Part 4

Deep dives

Tokens, labels, codes, and compliance.

  1. Lesson 10: Tokens and stored credentials

    FPAN, DPAN, MPAN, network tokens, and PAR, and which card number travels on each hop.

    19 minutes

  2. Lesson 11: Transaction types

    Channel, initiator, and credential: how to label every card payment, with an interactive classifier.

    7 minutes

  3. Lesson 12: Complete reference

    Authorization types, validity windows, statuses, codes, declines, disputes, and monitoring, brand by brand.

    23 minutes

  4. Lesson 13: Payments compliance

    PCI DSS, the self-assessment questionnaires, and the US rules and laws that apply to checkout.

    11 minutes

Put it together

Practice and look-ups

Trace one order, spot failures, and look up any term.

  1. Follow one order

    A $480 order traced day by day: where the money sits, from the first hold to the refund.

    4 minutes

  2. Where it breaks

    Six common checkout failures, the symptom you will see in support tickets, and the design fix.

    4 minutes

  3. Payments dictionary

    Payment terms and abbreviations in plain language, searchable and filterable by topic.

    Look up any time

Before lesson 1

Three short primers.

Five minutes here makes every lesson easier: the three moments of a card payment, the US rules that shape them, and the companies involved.

Start with three words

If you remember nothing else, remember this. A card payment happens in three separate moments, and most checkout confusion comes from treating them as one.

Authorization
A promise

The customer's bank agrees the funds are good and places a hold. Nothing has been paid.

Capture
A request

The merchant asks to collect some or all of the held amount, usually when the goods ship.

Settlement
The money

Banks move the funds. The merchant's account is credited, minus fees, a day or more later.

How the US is different

This guide follows US rules. Six of them shape almost every lesson that follows, so start here.

Authentication
3-D Secure is optional

No US law requires it. Merchants use it selectively, on risky orders, to shift fraud liability to the issuer.

Debit
You choose the route

Regulation II gives US merchants a choice of at least two unaffiliated debit networks, online too. The debit fee cap itself is back with the Federal Reserve after an October 2026 court ruling.

Four brands
Amex and Discover matter

American Express and Discover often run their own network, issuing, and acquiring, with their own rules, codes, and dispute steps.

Card fees
Surcharging is state by state

Credit card surcharges are allowed in most states within network caps (Visa 3%, Mastercard 4%), banned or limited in some, and never allowed on debit or prepaid cards.

Subscriptions
State laws lead

ROSCA sets the federal baseline. State automatic-renewal laws, led by California, add disclosure, reminder, and online-cancellation rules.

Disputes
The clock is short

Customers get about 120 days to dispute. For Visa disputes in the US, merchants may get as little as 9 days to respond.

Meet the cast

Every card payment passes through the same set of roles. Sometimes one company plays two roles (many payment providers act as gateway, processor, and acquirer at once), but the roles never disappear (with American Express, one company is often network, issuer, and acquirer at once). Tap each one.

The roles in a card payment
Sources for this guide (51)

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

Ready when you are

Start with
the checkout itself.

Lesson 1 shows why shoppers leave a checkout, what to fix in each part of it, and how to tell whether a fix helped.

Start lesson 1

Questions about payments? Email me. I read every note.

A phone showing a short checkout: a few fields and one clear Place order button. Place order fewersteps