> For the complete documentation index, see [llms.txt](https://developer.esw.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.esw.com/package-management/package-management-api/core-concepts.md).

# core concepts

- [Package](https://developer.esw.com/package-management/package-management-api/core-concepts/package.md): Create packages with parcel references, weights, and optional shipping details.
- [Consignee](https://developer.esw.com/package-management/package-management-api/core-concepts/consignee.md): Provide recipient and delivery-address details for a package.
- [Dangerous goods](https://developer.esw.com/package-management/package-management-api/core-concepts/dangerous-goods.md): Declare dangerous goods at package level and identify affected items.
- [Measurement and pricing](https://developer.esw.com/package-management/package-management-api/core-concepts/measurement-and-pricing.md): Send parcel dimensions, weights, shipping charges, and insurance values.
- [Package items and customs](https://developer.esw.com/package-management/package-management-api/core-concepts/package-items-and-customs.md): Describe package contents, item values, and customs information.
- [Package status](https://developer.esw.com/package-management/package-management-api/core-concepts/package-status.md): Interpret shipping, hold-release, and package operation statuses.


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