# 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)