Explain the word “federated” in terms of database servers and databases

The word “federated” in terms of database servers means SQL Server 2005 shares the database processing load across a group of servers by horizontally partitioning the data in a SQL Server database. These servers are managed independently, but cooperate to process the database requests from the applications; such a cooperative group of servers is called a federation. In terms of databases it means the databases can achieve very high levels of performance only if the application sends each SQL statement to the member server that has most of the data required by the statement. This is referred to as collocating the SQL statement with the data required by the statement. Collocating SQL statements with the required data is not a requirement unique to federated servers.