POS Glossary

Payment processing and POS terms explained without vendor spin. Every entry links to the review or comparison where it matters most.

Payments & Processing

Flat-Rate Processing

The payment processing model used by Square, Stripe, and similar providers: one fixed percentage per transaction regardless of card type. Predictable but expensive at high volume.

Interchange Fee

The wholesale fee Visa and Mastercard charge merchants for every card payment. Understanding interchange is the first step to knowing whether your POS is overcharging you on processing.

Interchange-Plus Pricing

The transparent payment processing pricing model where you pay actual interchange cost plus a fixed processor markup, instead of a bundled flat rate. The model that saves high-volume merchants the most money.

POS Software

KDS (Kitchen Display System)

A screen in the kitchen that replaces paper tickets, showing orders in real time. The KDS is the single biggest differentiator between Toast and Square for high-volume restaurant operators.

Compliance & Security

PCI DSS 4.0

The Payment Card Industry Data Security Standard version 4.0, mandatory from March 2025. What changed, what it costs a Level 4 merchant, and which POS vendors handle compliance for you.