What is data integration?
In reality, data integration is just another word for integrating systems. The main task of data integration is to secure a flow of data between different systems (for example an ERP system and a CRM system), each system dealing with the data with whatever business logic that is built into them. Very often, data integration transfers operational data from one system to the other, for example: Customers, Contacts, Items, Quotes, Orders, Invoices or Sales history.
But the scope of data integration can also include other types of data, for example either traditional master data (such as posting groups and other metadata that secure a consistent system setup and reporting) or it can basically be any table or field that you choose to map between the different systems. In reality, there are no limits to which data that can be relevant for data integration, it only depends on your system landscape and the business processes you are following.