Oracle Database supports the use of an Oracle home user, which can be specified at installation time. The Oracle home user is associated with an Oracle home and it cannot be changed after installation. Different Oracle homes on a system can share the same Oracle home user or use different Oracle home user names.
In previous releases on Windows operating systems, Oracle services were required to run as Local System privileges, which are fully privileged. This feature enables the database, listener, and job scheduler services to run with low and non-administrative user privileges to allow tighter control of security. The Oracle home user can be a built-in account or a Windows user account. A Windows user account should be a low privileged (non-Administrator) account to ensure that the Oracle home user has a limited set of privileges, ensuring that Oracle Database services have only those privileges required to run Oracle products. The Windows user account can be a Local User, a Domain User, or a Managed Services Account in general. However, Oracle RAC, Oracle Restart, and Oracle Grid Infrastructure installations require the use of the Domain User as the Oracle home user because a clusterwide identity is necessary.
Oracle Database Platform Guide for Microsoft Windows for information about running Oracle services on Windows platforms and different types of Windows user accounts