The dtexec command prompt utility is used to configure and execute Microsoft SQL Server Integration Services (SSIS) packages.
dtexec utility provides access to all the package configuration and execution features, such as connections, properties, variables, logging, and progress indicators.
dtexec utility lets you load packages from three sources:
- Microsoft SQL Server databases
- The SSIS service
- The file system
MSDN has more details here: http://technet.microsoft.com/en-us/library/ms162810%28v=SQL.105%29.aspx