> ## Documentation Index
> Fetch the complete documentation index at: https://docs.supercycle.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Platform overview
> How Supercycle builds on Shopify's products, orders, checkout, and customer accounts to run circular models
Supercycle is built inside Shopify, so you can offer rental and resale alongside your retail store and keep the checkout, payments, apps, and integrations you already use. This page explains what Supercycle adds and where it takes over.
***
## Supercycle and Shopify
| Shopify surface | How Supercycle uses it | Supported |
| ----------------- | --------------------------------------------------------------- | ----------------------------------------------------------- |
| Online Store | App blocks add rental and resale options to your theme | |
| POS | All four methods work at the counter | |
| Checkout | Native Shopify checkout, including Shopify Payments | |
| Returns | Supercycle runs its own returns, independent of Shopify returns | |
| Customer accounts | Supercycle's pages sit inside Shopify customer accounts | |
| Flow | Triggers and actions automate key tasks | |
| Markets | Supported | |
| B2B | Not supported | |
***
## Methods
[Methods](/documentation/overview/methods) are the ways you charge for the same item more than once. Supercycle supports four:
* **[Calendar](/documentation/methods/calendar/overview).** Charge for a set number of days.
* **[Subscription](/documentation/methods/subscription/overview).** Charge on a recurring basis until the item is returned.
* **[Membership](/documentation/methods/membership/overview).** Charge a recurring fee for an allowance of items that can be swapped in and out.
* **[Resale](/documentation/methods/resale/overview).** Sell items that aren't new, usually identified by serial number.
***
## Inventory
Once a product is imported, Shopify stops tracking its inventory and Supercycle manages it instead. That's what lets Supercycle track individual items and their availability, which rental needs when several orders are placed against one item across different dates.
### Items
[Items](/documentation/manage/inventory/items) are the individual units in your inventory. Each has a serial, so you can track its condition, status, and history over time. Attach the serial to the item with an RFID tag, barcode, or QR code to identify it in the warehouse or store.
### Availability
Supercycle's [allocation](/documentation/manage/cycles/allocation) assigns each new cycle to the item that keeps the most future availability open for upcoming customers.
***
## Orders
Supercycle uses native Shopify orders, so whatever a customer checks out with becomes their order. An order can mix rental products on different methods with retail items.
For each Supercycle-managed product in an order, Supercycle creates a [cycle](/documentation/manage/cycles/cycles). A cycle is assigned an item and tracks that item's fulfillment and receival. An order with several items creates several cycles.
***
## Returns
[Returns](/documentation/manage/returns/returns) are managed separately from Shopify's returns. Shopify ties one return to one order, which doesn't fit rental, where a customer may return items from several orders at once, such as on a membership.
When a customer requests a return from customer accounts, Supercycle creates a return that isn't tied to a single Shopify order, so it can handle those cases.