As taken from the Microsoft web-page for SQL Server Integration Services:
Microsoft Integration Services is a platform for building enterprise-level data integration and data transformations solutions. You use Integration Services to solve complex business problems by copying or downloading files, sending e-mail messages in response to events, updating data warehouses, cleaning and mining data, and managing SQL Server objects and data. The packages can work alone or in concert with other packages to address complex business needs. Integration Services can extract and transform data from a wide variety of sources such as XML data files, flat files, and relational data sources, and then load the data into one or more destinations.
Integration Services includes a rich set of built-in tasks and transformations; tools for constructing packages; and the Integration Services service for running and managing packages. You can use the graphical Integration Services tools to create solutions without writing a single line of code; or you can program the extensive Integration Services object model to create packages programmatically and code custom tasks and other package objects.