Introduction to Filtered Index - Improve performance

Filtered Index is a new feature in SQL SERVER 2008. Filtered Index is used to index a portion of rows in a table that means it applies filter on INDEX which improves query performance, reduce index maintenance costs, and reduce index storage costs compared with full-table indexes. When we see an Index created with some WHERE clause then that is actually a FILTERED INDEX. I am sure this feature will change how the indexes are created in SQL Server.