An interface which defines methods need to create binding value converter.
A method that will be executed when a value (of the binding property) should be converted to the observable model. For example: user types in a text field, but our business logic requires to store data in a different manner (e.g. in lower case).
A method that will be executed when a value should be converted to the UI view. For example we have a date object which should be displayed to the end user in a specific date format.