# Technical specification

This technical specification explains the content of the OS Names API and the methods you can use to call it.

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This technical specification extends the Infrastructure for Spatial Information in the European Community (INSPIRE) Geographical Names theme to ensure compliance with European open data initiatives.
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If you are not familiar with the OS Names API, please read the [overview documentation](https://docs.os.uk/os-apis/accessing-os-apis/os-names-api) before proceeding.
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## Core concepts

This specification does not cover core concepts that apply to all Ordnance Survey APIs.

Please read the following pages to learn more about OS API core concepts:

* [authentication](https://docs.os.uk/os-apis/core-concepts/authentication "mention")
* [error-codes](https://docs.os.uk/os-apis/core-concepts/error-codes "mention")
* [rate-limiting-policy](https://docs.os.uk/os-apis/core-concepts/rate-limiting-policy "mention")

## API reference

The OS Names API is an API, which returns queries to the service in either XML or JSON. The service offers two resources:

<table data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Find</strong></td><td>Return matched features based on a free text search.</td><td><a href="technical-specification/find">find</a></td></tr><tr><td><strong>Nearest</strong></td><td>Return the closest features to a pair of coordinates (X and Y).</td><td><a href="technical-specification/nearest">nearest</a></td></tr></tbody></table>