Meaning – The term realm, refers to a database of users, groups, and access control lists. A user must be defined in a realm to access any resource belonging to that realm.
A realm is a security policy domain defined for a web or applicationserver. The protected resources on a server can be partitioned into a set of protection spaces, each with its ownauthentication scheme and/or authorization database containing a collection of users and groups. For a web application, a realm is a complete database of users and groups identified as valid users of a web application or a set of web applications and controlled by the same authentication policy.
Example of usage – “In the file realm, the server stores user credentials locally in a file named keyfile. You can use the Administration Console to manage users in the file realm. When using the file realm, the server authentication service verifies user identity by checking the file realm. This realm is used for the authentication of all clients except for web browser clients that use HTTPS and certificates.”