Data classes are a Kotlin feature that allow us to write clean, simple classes that are commonly used to model data, such as API requests/responses and application state. They have have automatically derived equals(), hashCode() and toString() functions. This is an example of a simple data class Item that holds an id, title and subtitle: data class Item( val id: String, val title: String, val subtitle: String ) On Android we can use a data class to represent an item in a list.