The integration runtime is the compute infrastructure that Azure Data Factory uses to provide the following data integration capabilities across various network environments.
3 Types of integration runtimes:
Azure Integration Run Time: Azure Integration Run Time can copy data between cloud data stores and it can dispatch the activity to a variety of compute services such as Azure HDinsight or SQL server where the transformation takes place
Self Hosted Integration Run Time: Self Hosted Integration Run Time is software with essentially the same code as Azure Integration Run Time. But you install it on an on-premise machine or a virtual machine in a virtual network. A Self Hosted IR can run copy activities between a public cloud data store and a data store in a private network. It can also dispatch transformation activities against compute resources in a private network. We use Self Hosted IR because the Data factory will not be able to directly access on-primitive data sources as they sit behind a firewall. It is sometimes possible to establish a direct connection between Azure and on-premises data sources by configuring the Azure firewall in a specific way if we do that we don’t need to use a self-hosted IR.
Azure SSIS Integration Run Time: With SSIS Integration Run Time, you can natively execute SSIS packages in a managed environment. So when we lift and shift the SSIS packages to the data factory, we use Azure SSIS Integration Run Time.
Learn more about the concept by reading from the blog regarding SSIS by Intellipaat.