Azure Data Factory Integration Runtime acts as a mediator between on-prem data Stores and the Azure cloud. It is possible to run SQL Server Integration Services (SSIS) packages (which are developed on-prem) using Integration Runtime. This is an important feature as it can save considerable amount of time and effort required in recreating the SSIS packages in the Azure Data Factory environment.
Azure Data Factory Integration Runtime is the compute infrastructure that is required to provide data integration capabilities such as:
Data Flow: Execute an Azure Data Factory data flow in managed Azure compute environment
Data Movement: Copy data across data stores on the cloud and on premises. Supports in-built connectors, format conversion, column mapping etc.
Activity Dispatch: Dispatch and monitor transformation activities on a variety of Azure services such as Azure Databricks, Azure HDInsight, Azure SQL Database etc.
SSIS Package execution: Native execution of SQL Server Integration Services (SSIS) packages in a managed Azure compute environment.
Integration Runtime acts as a bridge between an activity and a linked service. To know more about activity in Azure Data Factory, please see this post. A linked service is target data store or compute service.
Azure Data Factory Integration Runtimes can be created using Management Hub, which is available in the Azure Data Factory UI.