# Shipping options

Shipping configuration answers two questions: where a method can deliver, and what it costs for this cart.
Thor exposes zones, methods, and rates so checkout can select eligible options from the buyer's current address and commerce context.

## Zones, methods, and rates

A zone groups the country locations a method serves.
A method describes the delivery option and can associate zones, channels, and an eligibility predicate.
Rates provide a fixed money amount or a relative amount and can have their own predicates and tax behavior.

For a standard-delivery option with a free-shipping threshold, distinguish the method from the conditions on its rates.
Test the exact threshold and currencies you support.
Use [cart predicates](/concepts/cart-predicate-language) for conditions on cart contents, amounts, or customer context.

## Let the cart resolve the choices

Set the required shipping address before reading `availableShippingMethods`.
Display returned methods and rates rather than maintaining a separate frontend list of country prices.
After the buyer changes an address or cart contents, refresh the options and verify the selected rate is still valid.

A valid method in Admin may be absent from a particular cart because its zone, currency, channel, or predicate does not match.
Debug those inputs before changing the display logic.

## Custom and external delivery

Use custom shipping lines only when your integration deliberately supplies the shipping amount.
For an external shipping integration, verify the supported public contract and handle unavailable-rate responses as part of checkout recovery.

Follow [Build a cart and checkout](/guides/storefront/cart-and-checkout) for selection and [ShippingMethodRateCreateInput](/api/admin-graphql/inputs/shipping-method-rate-create-input) for rate configuration.