Unix allows an user and a group to have the same name. In order to disambiguate, use the  @  prefix to force the name to be interpreted as a group. For example,  @dev  would mean the  dev  group and not the  dev  user. CAUTION Plugins can provide additional security realms which may be useful for incorporating Jenkins into existing identity systems, such as: The Security Realm, or authentication, indicates  who  can access the Jenkins environment. The other piece of the puzzle is  Authorization , which indicates  what  they can access in the Jenkins environment. By default Jenkins supports a few different Authorization options: Everyone gets full control of Jenkins, including anonymous users who haven’t logged in.  Do not use this setting  for anything other than local test Jenkins masters. Behaves exactly the same as Jenkins <1.164. Namely, if a user has the "admin" role, they will be granted full control over the system, and otherwise (including anonymous users) will only have the read access.  Do not use this setting  for anything other than local test Jenkins masters. In this mode, every logged-in user gets full control of Jenkins. Depending on an advanced option, anonymous users get read access to Jenkins, or no access at all. This mode is useful to force users to log in before taking actions, so that there is an audit trail of users' actions. This authorization scheme allows for granular control over which users and groups are able to perform which actions in the Jenkins environment (see the screenshot below). This authorization scheme is an extension to Matrix-based security which allows additional access control lists (ACLs) to be defined for  each project  separately in the Project configuration screen. This allows granting specific users or groups access only to specified projects, instead of all projects in the Jenkins environment. The ACLs defined with Project-based Matrix Authorization are additive such that access grants defined in the Configure Global Security screen will be combined with project-specific ACLs. 150 Project-based Matrix Authorization Strategy Matrix-based security Logged in users can do anything Legacy mode Anyone can do anything Authorization • plugin:active-directory[Active Directory] • plugin:github-oauth[GitHub Authentication] • plugin:crowd2[Atlassian Crowd 2]