A geodatabase domain is the set or range of valid attribute values that can be recorded for features collected or updated in the field.
Advantage of domains
Domains are essential in ensuring that data entry is accurate and consistent with the established standards. They enforce data integrity by restricting what data values a user can add to a particular field. Since domains are properties of the geodatabase, a single domain can be used for multiple feature classes within the geodatabase. This also helps ensure consistent data collection.
The domain Field Type can be short integer, long integer, float, double, text or date which corresponds with the field types listed in the previous table.
Note: ESRI refers to these as interchangably as domain field types or domain data types.
Types of domains
The Domain can be of 2 types: a range or coded value domains. Both are discussed in the following articles.