> For the complete documentation index, see [llms.txt](https://docs.os.uk/osngd/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/osngd/getting-started/os-ngd-fundamentals.md).

# OS NGD Fundamentals

OS NGD Fundamentals covers the core elements of OS NGD design, including data formats, coordinate reference systems used, data schema versioning, and data ordering and currency.

## Introduction

The following pages provide an overview of the OS National Geographic Database (OS NGD); they cover the core elements of its design, including data formats, the coordinate reference systems used, and how Change-Only Updates (COUs) will be provided, amongst other topics:

* [Terminology and access](/osngd/getting-started/os-ngd-fundamentals/terminology-and-access.md)
* [File formats and naming](/osngd/getting-started/os-ngd-fundamentals/file-formats-and-naming.md)
* [Data ordering and currency](/osngd/getting-started/os-ngd-fundamentals/os-ngd-data-ordering-and-currency.md)
* [COU supplies](/osngd/getting-started/os-ngd-fundamentals/cou-supplies.md)
* [Data schema versioning](/osngd/getting-started/os-ngd-fundamentals/data-schema-versioning.md)
* [Unique identifiers](/osngd/getting-started/os-ngd-fundamentals/unique-identifiers.md)
* [Coordinate reference systems](/osngd/getting-started/os-ngd-fundamentals/coordinate-reference-systems.md)
* [Attribute information for feature types](/osngd/getting-started/os-ngd-fundamentals/attribute-information-for-feature-types.md)

{% hint style="info" %}
These pages should be used in conjunction with the more detailed pages available within the [Data Structure section](/osngd/data-structure/data-structure-information.md) which are specifically focussed on the different OS NGD themes, collections and feature types.
{% endhint %}

***

## Discover OS NGD

Detailed documentation on OS NGD design and practical guides on how to apply OS NGD data:

<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><h3><span data-gb-custom-inline data-tag="emoji" data-code="1f4d6">📖</span> OS NGD Explained</h3><p>A high level summary of what the OS NGD is, how to access it and who can use it.</p></td><td></td><td><a href="/osngd/introduction-to-os-ngd/os-ngd-explained.md">OS NGD Explained</a></td></tr><tr><td><h3><span data-gb-custom-inline data-tag="emoji" data-code="2753">❓</span> FAQs</h3><p>Frequently asked questions on OS NGD data and the download service of OS Select+Build.</p></td><td></td><td><a href="/osngd/getting-started/faqs.md">FAQs</a></td></tr><tr><td><h3><span data-gb-custom-inline data-tag="emoji" data-code="1f469-1f3eb">👩‍🏫</span> OS NGD Webinars, Tutorials and Case Studies</h3></td><td>Learn more about the OS NGD through our webinars and tutorials. Case studies demonstrate how customers across numerous sectors are already using and benefiting from OS NGD data.</td><td><a href="/osngd/getting-started/os-ngd-talks-webinars-tutorial-videos-and-case-studies.md">OS NGD Webinars, Tutorials and Case Studies</a></td></tr></tbody></table>

## Explore OS NGD

In-depth information on OS NGD data, including structure, applications and news:

<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><h3><span data-gb-custom-inline data-tag="emoji" data-code="1f4e3">📣</span> OS NGD News</h3></td><td>Learn about new data and access enhancements recently released for the OS NGD.</td><td><a href="/osngd/os-ngd-news/os-ngd-news.md">OS NGD NEWS</a></td></tr><tr><td><h3><span data-gb-custom-inline data-tag="emoji" data-code="1f5c3">🗃️</span> Data Structure</h3></td><td>Data structure pages provide more detailed information about data available for OS NGD themes, collections and feature types.</td><td><a href="/osngd/data-structure/data-structure-information.md">Data Structure Information</a></td></tr><tr><td><h3><span data-gb-custom-inline data-tag="emoji" data-code="1f3a8">🎨</span> Styling OS NGD Data</h3></td><td>Resources for styling OS NGD data.</td><td><a href="/osngd/getting-started/styling-os-ngd-data.md">Styling OS NGD Data</a></td></tr></tbody></table>

## Get OS NGD

Try out OS NGD sample data, download it via OS Select+Build or access it through the OS NGD APIs:

<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><h3><span data-gb-custom-inline data-tag="emoji" data-code="1f5fa">🗺️</span> OS NGD Sample Data</h3></td><td>Try out OS NGD by downloading an area of sample data or visualising it online.</td><td><a href="/osngd/introduction-to-os-ngd/os-ngd-sample-data.md">OS NGD Sample Data</a></td></tr><tr><td><h3><span data-gb-custom-inline data-tag="emoji" data-code="1f4e5">📥</span> OS Select+Build</h3></td><td>Download OS NGD data using our bespoke download service, OS Select+Build.</td><td><a href="/osngd/getting-started/downloading-with-os-select+build.md">Downloading with OS Select+Build</a></td></tr><tr><td><h3><span data-gb-custom-inline data-tag="emoji" data-code="1f4cc">📌</span> OS NGD APIs</h3></td><td>Access OS NGD data using the OS NGD APIs to get started using OS NGD within desktop, web and mobile applications.</td><td><a href="/osngd/getting-started/access-the-os-ngd-api.md">Accessing OS NGD APIs</a></td></tr></tbody></table>


---

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