Content in eZ Publish is stored in attributes of content objects. A datatype describes the type of value that can be stored in an attribute and is the smallest possible entity of storage. It determines how a specific type of information should be validated, stored and retrieved. eZ Publish comes with a set of datatypes for, among other things, plain text, formatted text, images, email addresses and dates. This article explains how to create additional datatypes in eZ Publish 4, and explores how to take advantage of some of the new eZ Publish 4 features.