Once you have created a field, you can use it again in other sub-types of the same entity type. For instance, if you create a field for the article content type, you can also use it for the page content type, but you cannot use it for custom blocks or taxonomy terms. If there are fields available for re-use, after clicking <em>Add field</em> from the <em>Manage fields</em> page, you will see a list of available fields for re-use. After selecting a field for re-use, you can configure the sub-type-level settings.