- String (default)
The default type is String and you can change the type when setting up attributes if needed. The primary reason for changing type is how the attribute should be treated when segmenting. The String and Number types have the same options but the underlying comparators change from String to Numeric.
Date types have a separate set of options specifically tailored for dates (prior to X days ago, in the last X hours, in a date range)
If you are collecting a customer id by setting an external ID then you should also set the customer level attribute option to be YES if an attribute is related to the user, and should be synced across all devices that are linked to that user's ID. First name is a good example of this if a user changes their first name then you will probably want personalised messages sent to all the user's devices to use the new first name.