# UDI Identifiers

## Introduction

Umbraco stores identifiers in UDI format for most Umbraco object types. This identifier stores all of the metadata required to retrieve an Umbraco object and is parse-able within text. Example: `umb://document/4fed18d8c5e34d5e88cfff3a5b457bf2`. UDI's can be used in many of the querying APIs.

{% hint style="info" %}
UDI is currently not an acronym for something. There is no official definition of what it's short for. Therefore it's called *UDI*
{% endhint %}

## Format

An Umbraco UDI consists of three parts: the scheme, the type and a GUID Identifier. For example: `umb://document/4fed18d8c5e34d5e88cfff3a5b457bf2`.

Breaking it down:

1. The scheme is `umb://` - this is always the same and makes it identifiable as an Umbraco UDI
2. The type is `document` - so in this is an Umbraco node, but it could also be `media`, `member`, etc.
3. The GUID Id is `4fed18d8c5e34d5e88cfff3a5b457bf2` - this is a GUID (dashes removed) which is randomly generated when the item is being created

## Usage

You can use UDIs in some of the Querying and Management/Service APIs.

There are 2 types of UDIs:

## GUID UDI

* [API Reference for Umbraco 13](https://apidocs.umbraco.com/v13/csharp/api/Umbraco.Cms.Core.GuidUdi.html)

## String UDI

* [API Reference for Umbraco 13](https://apidocs.umbraco.com/v13/csharp/api/Umbraco.Cms.Core.StringUdi.html)