Describe SQL Server Integration Services
SQL Server Integration Services (SSIS) is a platform for building complex Extract Transform and Load (ETL) solutions. SSIS is a component within SQL Server and consists of a Windows service that manages the execution of ETL workflows, along with several tools and components for developing those workflows. It's typically used to develop data integration pipelines for on-premises data warehousing solutions. It can also be used to create data migration pipelines when migrating data between different systems.
SSIS is primarily a control flow engine that manages the execution of workflows. Workflows are held in packages, which can be executed on demand, or on a schedule. When you develop SSIS packages, the task workflow is referred to as the control flow of the package. A control flow can include a specific task to manage data flow operations. SSIS executes these Data Flow tasks by using a data flow engine that encapsulates the data flow in a pipeline. Each step in the Data Flow task operates in sequence on a rowset of data as it passes through the pipeline.
An SSIS solution usually consists of one or more SSIS projects, each containing one or more SSIS packages.
SSIS projects
From SQL Server 2012, a project is the unit of deployment for SSIS solutions. You can define project-level parameters to enable users to specify run-time settings, and project-level connection managers that reference data sources and destinations used in package data flows. You can then deploy projects to an SSIS catalog in a SQL Server instance, and configure project-level parameter values and connections as appropriate for execution environments.
SSIS packages
A project contains one or more packages, each defining a workflow of tasks to be executed. The workflow of tasks in a package is referred to as its control flow. A package control flow can include one or more Data Flow task, each of which encapsulates its own data flow pipeline. Packages can include package-level parameters so that dynamic values can be passed to the package at run time. In previous releases of SSIS, deployment was managed at the package level.