# self

### Description

`self` is used to refer to the current [instance](https://docs.atfinity.io/guides/glossary/instance) where you use it.

{% hint style="info" %}
This operator can only be used with [calculated information](https://docs.atfinity.io/rule-language/operators/special-operators/broken-reference).
{% endhint %}

### Example

```
CONCAT(self.last_name, ", ", self.first_name)
```

This [expression](https://docs.atfinity.io/rule-language/expressions) calculates the full name of a person, by getting the information from the fields `first_name` and `first_name`.

If the expression is attached to an instance of the ‘Person’ [ontology](https://docs.atfinity.io/guides/glossary/ontology), `self` tells the system to look for the field's first name within that instance.

If there is an Instance with the values for *Information Fields* `first_name` and `last_name` as Britta Johansdottir, this will return *'Johansdottir, Britta'.*