> For the complete documentation index, see [llms.txt](https://docs.smartbotpro.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.smartbotpro.io/scripts/variables/variable-ref.md).

# Variable %ref%

### First a little theory

{% hint style="info" %}
**A referral link** is a link that contains information from where the user follows it. 
{% endhint %}

For example, we place a link in an advertising campaign, and users get to our bot through it. 

The bot reads the link, extracting the %ref% parameter, which specifies the referral source. 

Description of the %ref% and %ref\_source% parameters can be seen in the "Variables" section:

![](/files/EzqwflriYTMGcm5E9Bhb)

### How to use it?

Write a link like this...

* For VK groups:

> [https://vk.me/группа?ref= ](https://vk.me/group?ref=)

* For Telegram: 

> <https://t.me/channel?start=>

Instead of "group" or "channel" - the name of your community from the address bar. After the = sign, indicate in Latin letters the source where you place this link, for example, "advertisement".

So the finished link might look like this:&#x20;

* <https://vk.me/club192634149?ref=advertisement>
* <https://t.me/smartbotpro?start=advertisement>

After clicking on the link, the "reklama" parameter will be saved as a person's user variable, and in the future, the parameter can be used for conditions in the script.

![](/files/flyPnolh5xnUGjC9glTL)

Now you know how to create and apply referral links in Smartbot Pro!