You can administer multiple servers by designating Central Management Servers and creating server groups.
What is a Central Management Server and server groups?
An instance of SQL Server designated as a Central Management Server maintains server groups that contain the connection information for one or more instances. You can execute Transact-SQL statements and Policy-Based Management policies at the same time against server groups. You can also view the log files on instances managed through a Central Management Server.
Basically a Central management Server is central repository containing a list of your managed servers. Versions earlier than SQL Server 2008 cannot be designated as a Central Management Server.
Transact-SQL statements can also be executed against local server groups in Registered Servers.
Create Central Management Server and server groups
To create a Central Management Server and server groups, use the Registered Servers window in SQL Server Management Studio. Note that the Central Management Server cannot be a member of a group that it maintains.
For how to create Central Management Servers and server groups, see Create a Central Management Server and Server Group (SQL Server Management Studio).