SQL Server Integration Services (SSIS)

SQL Server Integration Services (SSIS) allows you to integrate smoothly with other applications and data sources.
You can use Integration Services to copy or download files, send e-mail messages in response to events, update data warehouses, clean and mine data, and manage SQL Server objects and data.
In SQL Server 2005 and higher, Data Transformation Services (DTS) is no longer installed with SQL Server. All DTS related tasks are now performed with SSIS.

Where Has DTS Gone?

If you have been working with earlier versions of SQL Server (SQL Server 2000 and earlier), you are probably familiar with DTS. DTS allowed you to transfer data between disparate sources into one or more destinations.
Well, starting from SQL Server 2005, DTS has been deprecated. DTS is no longer included with your SQL Server installation.
If you need DTS-type functionality in SQL Server 2008, you will need to use SQL Server Integration Services.

Backwards Compatibility

For backwards compatibility, Microsoft has provided installation files that provide run-time support for DTS packages. This will be useful if you have already created DTS packages in an earlier version of SQL Server. For more information see Support for Data Transformation Services (DTS) in SQL Server 2008 on the MSDN website.

SQL Server Express & SSIS

SQL Server Integration Services is not available in the Express or Workgroup editions of SQL Server. If you need to use Integration Services, you need at least SQL Server Standard edition. And, if you need to use advanced features (such as data mining, text mining and cleansing or fuzzy transforms), you will need SQL Server Enterprise edition.
For more information on SQL Server Integration Services, check out SQL Server Integration Services on the MSDN website.