# App Variables and Runtime Properties

In most Apps you will need some variables that are not part of the data saved in the database. For example, if you want a search box in a User Interface, the search text needs to be saved somewhere (and used for filtering the data to be displayed).

Variables are called **Runtime Properties** in Appfarm.

Runtime Properties may be added to a built-in Data Source called **App Variables** (for holding single variables to be used in your App), or they may be added to **Data Sources**.

A **Runtime Property** may be of type **Value or Function.** 

* Value is used whenever you want to set that value yourself (e.g. from a User Interface, or from an Update Object Action Node)
* Function is a calculated property. E.g. you may have a Runtime Property `Full name` with a function `return firstName + " " + lastName`

### Video

You may see a video on App Variables and Runtime Properties below.

{% embed url="<https://www.loom.com/share/27037cba485945419a883d93d0c131ae>" %}
A video on App Varialbes and Runtime Properties
{% endembed %}

### Documentation

Relevant articles in our documentation:

* [App Variables](https://docs.appfarm.io/reference/apps/data#app-variables)
* [Runtime Properties](https://docs.appfarm.io/reference/apps/data#runtime-properties)
* [Functions](https://docs.appfarm.io/reference/platform-concepts/functions)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.appfarm.io/appcademy/appfarm-fundamentals/app-data-fundamentals/app-variables-and-runtime-properties.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.