> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-downloads/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/os-downloads/products/addresses-and-names-portfolio/addressbase/addressbase-getting-started-guide/prerequisites.md).

# Prerequisites

## System requirements <a href="#bookmark3" id="bookmark3"></a>

AddressBase data is an addressing gazetteer that can be used within GIS and database systems. For details of Ordnance Survey’s licensed partners, who can incorporate the AddressBase products in their systems, please see the [systems/software page](https://www.ordnancesurvey.co.uk/business-government/tools-support/gis/software) on the Ordnance Survey website.

Ordnance Survey does not recommend either suppliers or software products as the most appropriate system depends on many factors, such as the amount of data being taken, resources available within the organisation, the existing and planned information technology infrastructure and the applications that AddressBase products can be used for.

However, as a minimum, the following elements will be required in any system:

* A means of reading the data, either in its native format, or by translating it into a file format or for storage in a database.
* A means of storing and distributing the data, perhaps in a database or through a web-based service.
* A way of visualising and querying the data, typically a GIS.

## Backup provision of the product <a href="#bookmark4" id="bookmark4"></a>

You are advised to copy the supplied data to a backup medium.

## Typical data volumes <a href="#bookmark5" id="bookmark5"></a>

For reading purposes, it is recommended to store the data on a single hard disc. This will speed up the ability of your computer to read the data. Unzipped file sizes for the full supply of each product are as follows:

| Product                  | Unzipped CSV file size | Unzipped GML file size |
| ------------------------ | ---------------------- | ---------------------- |
| AddressBase              | 6Gb                    | 32Gb                   |
| AddressBase Plus         | 16Gb                   | 78Gb                   |
| AddressBase Plus Islands | 450Mb                  | 2Gb                    |


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