# Getting started with CSV

## What is a CSV file?

A comma-separated values (CSV) file is a common interchange format for spreadsheets and databases which facilitates a simplistic use of data. Each field is either textual or numeric. Within the CSV, each field is separated from the next by a comma. CSV file format is universally supported for easy ingestion into all major database products.

Please be aware that CSV files are designed to be opened in a database or GI system, and opening them in other software applications could corrupt the data. In particular, Excel has a row limit which might be exceeded by some of our CSV files containing OS NGD data, depending on the order you placed and its size. We recommend that you load CSV files containing OS NGD data directly into a database or GI system, rather than trying to open these files in Excel.

{% hint style="info" %}
Change-Only Update (COU) files are only available for CSV data supplies of the OS NGD.
{% endhint %}

{% hint style="info" %}
If you are using a large Area of Interest (AOI) or a full GB supply of data, for performance reasons we would suggest you load the CSV data into a database rather than trying to open directly in a GI system.
{% endhint %}

### Key features of OS NGD CSV format

CSV offers users the following key features:

* Change-Only Update (COU) files are only supplied in CSV format (they are not supplied in GeoPackage format)
* Geometry provided as Well-Known Text (WKT)
* Header rows included in the file
* There will be one record per line in each file
* Fields will be separated by commas
* Where string fields contain commas, they will be delimited by double quotes
* Double quotes inside strings will be escaped by doubling
* Records will be terminated by Carriage Returns and Line Feeds
* CSV files will be Unicode encoded in UTF-8


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