> For the complete documentation index, see [llms.txt](https://readme.directual.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://readme.directual.com/data/data-structures.md).

# Data Structures

Data structures are a database for your app.

Objects from data structures:

* are processed in [scenarios](/scenarios/principles-of-scenarios.md)
* are processed in reports
* can be accessed via [API-endpoints](/api-integrations/api-endpoints-security-layer.md) and [Webhooks](/api-integrations/webhooks.md)

By default, the following object properties exist:

* **ID**. This is a unique key to the object. If you change the ID, a new object will be created
* **Who**. Who changed/created an object. Can't be changed from UI, API, or scenario
* **dateCreated**. The date and time when the object was created. Can't be changed from UI, API, or scenario
* **dateChanged**. The date and time when the object was changed. Can't be changed from UI, API, or scenario

{% hint style="warning" %}
The maximum **ID** length is 36 characters!
{% endhint %}

You can add custom fields (properties) and groups for your data structure. Each field has to be a [type from the list](/data/data-types.md).

{% embed url="<https://youtu.be/-14a_hoVUw4>" %}

### Structure visible name

**Y**ou can set up a visible name of a structure by configuring the fields. The name will be displayed in the objects near links to that structure, in [cards](/web-pages/components/legacy-components/cards.md), and in selections [form](/web-pages/components/legacy-components/form.md#link-and-arraylink-quick-search-option).