What is a Linked Server?

What is Linked Servers or Database Links? 

Don't be confused by the two terms; both are the same. In SQL Server it is called a Linked Server whereas in Oracle it's DBLinks (Database Links). Linked Servers allows you to connect to other database instances on the same server or on another machine or remote servers.

 It allows SQL Server to execute SQL scripts against OLE DB data sources on remote servers using OLE DB providers. The remote servers can be SQL Server, Oracle etc. which means those databases that support OLE DB can be used for linking servers.