# Case sensitivity and your data

When you send data to Customer.io, you should format it consistently so it’s easier to reference in liquid to personalize messages and send data to other platforms.

## When is data case sensitive?[](#when-is-data-case-sensitive)

1.  **[AttributeA key-value pair that you associate with a person or an object—like a person’s name, the date they were created in your workspace, or a company’s billing date etc. Use attributes to target people and personalize messages.](/journeys/attributes/) names** are always case sensitive.
    *   You can save both `first_name` and `First_Name` to a profile; those fields will not merge together.
    *   This is also the case for [reserved attributes](/journeys/attributes/#reserved-attributes) like [`timezone`](/journeys/timezone-match/) and `unsubscribed`. You must lowercase these attributes to use time zone match or our global subscription functionality.
2.  **Attribute values** are case sensitive in [liquidA syntax that supports variables, letting you personalize messages for your audience. For example, if you want to reference a person’s first name, you might use the variable `{{customer.first_name}}`.](/using-liquid) logic. For instance, if a person has a `favorite` attribute with the value `Sports`, the `else` statment below would render because of the different casing:
    
    ```html
    {% if customer.favorite == "sports" %}
        Come to the game!
    {% else %}
        Try swing dancing!
    {% endif %}
    ```
    
3.  **Liquid logic** - this is true for strings and booleans:
    
    ```html
    {% if customer.favorite == "sports" %}
        This renders for people with a value of `sports`.
    {% else %}
        This would render for people with any other value, including a different casing of sports.
    {% endif %}
    ```
    
    ```html
    {% if customer.unsubscribed == true %}
        This renders for people with a value of `true`.
    {% else %}
        This would render for people with any other value, including a different casing of true.
    {% endif %}
    ```
    
4.  In-app message [**page rules**](/journeys/send-in-app-message/#page-rule)

## When is data NOT case sensitive?[](#when-is-data-not-case-sensitive)

1.  **[AttributeA key-value pair that you associate with a person or an object—like a person’s name, the date they were created in your workspace, or a company’s billing date etc. Use attributes to target people and personalize messages.](/journeys/attributes/) *values*** are case insensitive in UI filters, segment conditions, and workflow logic conditions. For example, people with a `language` attribute value of `Fr` or `fr` will both receive the email variant for `fr`.
    
2.  **[EventSomething that a person in your workspace did. Events can trigger campaigns, add people to segments, etc, and you can use properties from events to personalize messages.](/events/) names** - in most cases, an event `course_signup` sent to your workspace is the same as `Course_signup`. When you’re sending data out of Customer.io, make sure you’re sending the format your destinations would expect.
    
    **Conversion criteria are the exception to this rule.** Event names used in [conversion criteria](/journeys/campaign-conversions/#event) are case sensitive, so `course_signup` and `Course_signup` would be treated as distinct events in this case.
    
3.  Trigger names for [transactional messages](https://fly.customer.io/workspaces/last/journeys/transactional)