Essential database server vocabulary

ArcSDE geodatabases for SQL Server Express	These are the geodatabases that are stored on a database server.
Database server	Within ArcGIS software, the term database servers refers to instances of Microsoft SQL Server Express that have been enabled to store geodatabases.
Dbo	This is a group in SQL Server database management systems (DBMS); any user who is in the SQL Server fixed server role sysadmin is a dbo. On database servers, all server administrators are members of dbo.
Desktop geodatabases	In some ESRI documentation, the ArcSDE geodatabases for SQL Server Express that are licensed through ArcGIS Desktop or ArcGIS Engine are referred to as Desktop geodatabases.
Geodatabase administrator	A geodatabase administrator is a Windows-authenticated user assigned to the geodatabase database owner role (db_owner) in the SQL Server Express instance. This user can perform administrative tasks, such as administering other users' geodatabase permissions, making a backup of the geodatabase, and compressing the geodatabase.
Server administrator	A server administrator is a Windows-authenticated user who manages database servers. This user is a dbo and is responsible for the administration tasks on the database server. Every database server must have a server administrator. This user is added when the SQL Server Express instance is enabled for geodatabase storage. See The administrative user for database servers for more information.
Windows authentication	Windows authentication is a method for identifying an individual user with credentials supplied by the Windows operating system of the user's computer.
Workgroup geodatabases	In some ESRI documentation, the ArcSDE geodatabases for SQL Server Express that are licensed through ArcGIS Server Workgroup are referred to as Workgroup geodatabases.