> For the complete documentation index, see [llms.txt](https://docs.copperx.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.copperx.io/getting-started/key-concepts-and-terminology.md).

# Key Concepts & Terminology

1️⃣ **Non-Custodial**

* Copperx does **not** hold or manage your funds.
* All payments are sent directly to your connected wallets.
* You maintain full custody, transparency, and control.

***

2️⃣ **Checkout**

* A hosted payment page or API flow for **one-time crypto payments**.
* Features: blockchain address generation, live payment tracking, and confirmation.
* Use cases: eCommerce, service payments, custom flows.

***

3️⃣ **Invoicing**

* Create and send **crypto invoices** to customers.
* Features: due dates, itemized billing, automated reminders.
* Use cases: B2B services, agency billing, crypto-based contracts.

***

4️⃣ **Subscription**

* Set up **recurring crypto payments** on fixed schedules (monthly, annually, etc.).
* Manage through Copperx’s API or dashboard.
* Use cases: SaaS products, memberships, ongoing services.

***

5️⃣ **Webhook**

* Real-time callbacks that notify your system about key events.
* Example events:
  * Payment completed
  * Invoice overdue
  * Subscription renewed or canceled
  * Checkout session expired
* Purpose: Automate backend actions like account upgrades or service provisioning.

***

6️⃣ **Test Mode**

* A **sandbox** to simulate payments, subscriptions, and invoices.
* Operates on testnets (e.g., Polygon Amoy, Ethereum Sepolia).
* Requires test tokens (available from [Copperx faucet](https://dashboard.copperx.dev/faucet)).

***

7️⃣ **Supported Chains**

* Blockchains Copperx integrates with for crypto payments.
* Example [supported networks](https://copperx.io/payment-methods):
  * Ethereum
  * Polygon
  * Solana
  * BNB Smart Chain
  * Base
  * Arbitrum
  * Optimism
  * Tron
* Tokens supported: USDC, DAI, ETH, BTC, POL (varies by chain).

### 📘 Summary

Understanding these concepts helps you:\
✔ Select the right payment model (checkout, invoice, or subscription)\
✔ Implement webhook-driven automations\
✔ Test safely in development mode\
✔ Choose the appropriate blockchain and token for your integration