User Account Control (UAC) is a technology and security infrastructure first introduced with Microsoft's Windows Vista operating system. It aims to improve the security of Microsoft Windows by limiting application software to standard user privileges until an administrator authorizes an increase in privilege level. In this way, only applications that the user trusts receive higher privileges, and malware should be kept from receiving the privileges necessary to compromise the operating system. In other words, a user account may have administrator privileges assigned to it, but applications that the user runs do not also have those privileges unless they are approved beforehand or the user explicitly authorizes it to have higher privileges.
In Vista, there are basically two types of users: the standard users and the administrator. But administrator can modify each user’s privileges for a particular purpose. In the following table, the typical user group types and privileges are listed:
| User type | Privileges | Vista Edition |
| Administrator | The admin type of users has all privileges to perform all tasks in the system, such as, install software, backup/restore systems, monitoring system, setup other users and change their privileges etc. | All |
| Anonymous Logon | This is a special identity provided to anyone who has access to the system but doesn’t authenticate in anyway. Admin user need to assign specific such as access certain file folders to this type of users. | All |
| Backup Operators | This type of user has privilege to read/write files to all folders so that they can perform the task of system backup and restore. | All |
| Batch | This type of user can log on the system through some batch process, such as the scheduled batch utility tasks. | All |
| Event Log Readers | This type of user has the same permission as an admin to view all event log of the system, including the security log. (Standard user can only view part of the system log via Event Viewer.) | All |
| Guest | This is a build-in account used to provide someone without permissions on the machine to log on and access limited resources of the system. | All |
| IIS_IUSRS (or IUSR) | This type of user has permissions to accounts used by web pages within IIS. Vista uses IUSR for anonymous access to web pages published through IIS. | Business, Enterprise and Ultimate |
| Interactive | This is a special identity that is logged on either directly to the machine or through a remote desktop connection. This group is opposite of the Network type of user. | Business, Enterprise and Ultimate |
| Local Service | This is a special identity set to run Local Services of a particular machine. By default, this group has the same permissions as standard users. | All |
| Network | This is a special identity that includes users to access Vista resources over the network (other than via a remote desktop connection). This group is opposite of the Interactive special identity. | Business, Enterprise and Ultimate |
| Network Configuration Operators | This is a group of users with privileges in relation to networking within Vista, who can manage the configuration of networking features to Standard User accounts. | All |
| Network Service | This is a special identity that includes any service set to run as a Network Service. | All |
| Performance Log User | This group of users has privileges in relation to the Vista Windows Reliability and Performance Monitor. | Business, Enterprise and Ultimate |
| Performance Monitor User | This group of users has privileges in relation to the Vista Windows Reliability and Performance Monitor. | Business, Enterprise and Ultimate |
| Service | This is a special identity that includes any service to run as a Service. By default this type of user has the same permissions as a standard user. | All |
| Standard User | This group is for all users. By default, Vista places all new users into this group unless you change the account type to Administrator. | All |
| System | This is a special identity that is the Vista OS itself. By default this group has all the permissions that the OS needs. | All |