Payment processing is written in language designed to be confusing. This page is the antidote: what a processor actually is, and what every term you'll see on a ProcessorWatch profile — reserves, ISO, high risk, MID, interchange-plus — means in plain English, with a real example of how it hits your business.
Every card swipe is a lot like making a phone call. Five pieces have to work together or the call doesn't connect. Here's each piece of your phone, matched to its twin in the payments world, in the simplest way we can explain it.
Your phone
Your cell phone
In payments
The card terminal
So you have a cell phone — iPhone or Android. In payments, that's the equivalent to your hardware: a Pax, Dejavoo, Ingenico, Clover, or the checkout page on your website. On its own, it's just a piece of plastic and glass, but it can be important to have, only if you have the other pieces in place.
Your phone
The phone app (dialer)
In payments
The payment gateway
Your phone needs an app to actually dial the numbers. In the same way, a terminal needs a payment gateway — the software layer that takes the card, encrypts it, and gets it ready to send. No gateway, no call.
Your phone
SIM card & carrier plan
In payments
The processor
You can dial all day, but nothing happens without a SIM and a plan with a carrier. The processor is that carrier — the company you've partnered with that actually carries your transaction out to the world and brings the money back.
Your phone
Cell towers
In payments
The card networks (Visa / Mastercard)
Your call travels across the carrier's towers to reach the other person. In payments, the processor hands the transaction to Visa, Mastercard, Discover, or Amex — the backbone of the whole system.
Your phone
The person you're calling
In payments
The cardholder's bank
Someone has to pick up on the other end. The customer's issuing bank is who actually approves or declines the charge and eventually releases the money back down the same chain into your account.
Put it together: your terminal uses a gateway to reach your processor, which hands the transaction to the card networks, which ring the cardholder's bank. Money comes back the same way. If any one piece is missing, the call — and the payment — simply doesn't go through.
A payment processor is the company that carries card transactions between your business, the customer's bank, and the card networks (Visa, Mastercard, Discover, American Express), and then moves the money into your bank account.
When someone taps a card at your counter or checks out on your site, roughly this happens in two seconds:
Most of the pain in merchant services doesn't come from step 1–3. It comes from step 4, and from every line item, hold, and contract clause bolted onto it. That is what the rest of this glossary explains.
We link back to these definitions from processor profiles so you can decode any concern or praise without leaving the page.
Also called: Acquirer · Merchant services provider
The company that carries card transactions from your terminal or website to the card networks (Visa, Mastercard, etc.) and back, and moves money into your bank account.
When a customer taps a card at your café, the processor is what tells Visa to approve it, then deposits the money in your checking account a day or two later.
A middleman company that sells accounts on behalf of a bigger processor. Most 'merchant services' brands you have heard of are actually ISOs sitting on top of one or two large processors.
You sign with a local company called 'ABC Payments.' Your statement, your money movement, and your risk decisions are actually being handled by Fiserv or TSYS behind the scenes. ABC Payments is the ISO; Fiserv or TSYS is the real processor.
The account number the processor uses to identify your business. Everything — pricing, deposits, chargebacks — is tied to your MID.
If a processor decides to freeze your account, they freeze your MID. If you move to a new processor, you get a new MID.
A business the processor thinks is more likely to generate chargebacks, fraud losses, or regulatory trouble. High-risk merchants pay higher rates and often have money held back as protection.
Common high-risk categories: CBD, firearms, adult content, nutraceuticals, credit repair, travel, coaching/high-ticket digital, subscription boxes, debt collection, and most 'free trial → auto-billed subscription' models. If a mainstream processor won't board you, you're probably being classified as high-risk.
Money the processor keeps out of your deposits to cover future chargebacks or refunds. Usually a percentage of every sale, held for a set number of months.
A 10% rolling six-month reserve on $50,000/month of volume means $5,000 of every month's revenue gets held for six months before it releases. That's $30,000 of your money sitting with the processor at any given time.
When a customer's bank pulls a payment back out of your account after the customer disputes the charge. The money is taken from you until you either win the dispute or absorb the loss.
A customer buys $400 in goods, receives them, then tells their bank 'I never authorized this.' You have to produce receipts, delivery proof, and signed authorization within a short window — or the $400 (plus a fee) is gone.
The application and approval process before a processor lets you accept cards. They look at your business, your bank statements, and your processing history to decide whether to take the risk of you as a customer.
For a mainstream retail shop, onboarding can be a same-day approval. For a high-risk merchant, expect requests for 3–12 months of bank statements, prior processor statements, a website review, and sometimes a personal credit check.
Pricing where you pay the actual card-network cost of each transaction plus a fixed, disclosed markup. It's the transparent option.
'Interchange + 0.30% + $0.10' means the processor charges you exactly what Visa or Mastercard charge them, plus 0.30% and 10 cents. You can verify every line. Almost every merchant should be asking for this.
Pricing that lumps card transactions into 'qualified,' 'mid-qualified,' and 'non-qualified' buckets — with the processor deciding which bucket each transaction falls into. Very common, rarely in the merchant's favor.
You're quoted a great 'qualified rate' of 1.59%. Then every rewards card, every corporate card, and every keyed-in transaction ends up in a 'non-qualified' bucket at 3.5%. Your real effective rate is much higher than the quote.
One simple percentage on every transaction, regardless of card type. Easy to understand. Almost always more expensive than interchange-plus once you cross meaningful volume.
Stripe and Square default to something like 2.9% + $0.30. Above roughly $20,000/month in card volume, most merchants save money moving off flat-rate.
The bank that actually holds the license from Visa and Mastercard to process card payments. Every processor is either an acquirer or is riding on one.
When your ISO says 'we had to escalate to the bank,' they mean the acquirer. The acquirer is the entity that can freeze your account or release a reserve.
A model where the processor holds one giant merchant account and sub-accounts you underneath it. Fast to sign up. Also fast to shut down.
Stripe, Square, PayPal, and Shopify Payments are all PayFacs. That is why you can start accepting cards in ten minutes — and also why they can pause your payouts overnight without a phone call.
The security standard everyone who touches card data has to follow. Processors will bill you either a monthly PCI fee, a non-compliance fee, or both.
Most small merchants complete an annual self-assessment questionnaire. Miss it and you'll typically see a $20–$40/month non-compliance fee appear on your statement automatically.
The movement of money from the processor into your bank account after a batch of transactions is closed.
'Next-day funding' means Monday's sales hit your bank Tuesday. 'Same-day funding' means Monday's sales are usable Monday evening — usually only if you bank with the acquirer.
The small monthly fees on top of the processing rate — monthly statement, batch fee, IRS reporting, network access, PCI, gateway. Individually tiny. Collectively material.
On $10,000/month of volume, $60 in incidental fees is another 0.60% added to your effective rate. This is where processors that quote a 'low rate' quietly make it back.
The software layer that connects your website or POS to the processor. Sometimes bundled with your processor, sometimes a separate bill.
Authorize.net is a gateway. If your processor is First Data and your gateway is Authorize.net, you're paying two companies for one checkout.
Any transaction where the card isn't physically dipped, tapped, or swiped — meaning ecommerce, phone orders, and keyed-in transactions. Higher risk, higher rates.
The same $100 sale can cost you 1.9% in-person and 2.6% online. That's not the processor overcharging — the card networks themselves charge more for CNP.
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