(Thanks to [Ted & Gustaf](🔗) for this example.)
One usage scenario could be to check for a cookie that says that the visitor has previously completed a purchase on the website; that is, is a returning customer.
## Create the settings and criterion classes
All visitor group criteria require a `settings
` class and a `criterion
` class.
The `
settings
` class is used to persist any settings available to editors when creating new visitor groups.The `
criterion
` class contains the logic to determine whether or not a visitor belongs to the visitor group.
You should create the two classes in a suitable folder structure:

## Implement the settings class
The only setting required for this visitor group criterion is the cookie name you should look for.
First, make the `
CookieExistsCriterionSettings
` class inherit the `CriterionModelBase
` class:Add a public property to let editors specify the cookie name:
If you need custom validation logic when a criterion is saved, you can make your settings class implement the `
IValidateCriterionModel
` interface (this is optional). By implementing that interface’s `Validate
` method, you can customize how settings are validated before saving a criterion for a visitor group.The abstract `
CriterionModelBase
` class requires you to implement the `Copy()
` method. Because you are not using complex reference types, you can implement it by returning a shallow copy as shown (see [Create custom visitor group criteria](🔗)):
This is the complete `CookieExistsCriterionSettings
`Â class:
## Implement the criterion class
Make the `
CookieExistsCriterionclass
` inherit the abstract `CriterionBaseclass
` with the settings class as the type parameter:Add a `
VisitorGroupCriterion
` attribute to set the category, name, and description of our criterion (for more available `VisitorGroupCriterion
` properties, see [Create custom visitor group criteria](🔗):
The abstract `
CriterionBase
` class requires you to implement an `IsMatch()
` method which determines whether the current user matches this visitor group criterion. You should check if a specific cookie exists based on the criterion settings:
The criterion class appears as follows:
Note
You access the criterion settings instance through the Modelproperty.
## Test the new criterion
To test the criterion, create a new visitor group using the new cookie criterion.
Set the cookie name to **.EPiServerLogin**, the name of the cookie created when a user logs in:

If you are on CMS version 10 or 11, it will look like this:

Select some content in the editor that should only be displayed to users currently logged in to Episerver.

Click **Personalized Content** and select the new **Episerver User** visitor group.

This content is now only displayed to users logged into Episerver:

After publishing the page, you see this:

However, if you log out, you no longer see the personalized content.
