Prerequisites
Before you start the initial data transfer, you should have answered the following questions:
The objects to be transferred depend on the business application that you will use. If you use sales and distribution processing, for example, you should transfer the material masters as well as the sales documents from your legacy system.
The objects can be transferred manually or automatically, using an SAP standard program or your own program.
The following process applies to transferring data automatically using the SAP standard conversion program and the Data Transfer Workbench.
Process Flow
When data is initially transferred, data from the legacy system is converted into a sequential data transfer file and then transferred to the R/3 System using an SAP data transfer program. The data transfer file is the prerequisite for successfully transferring data as it contains the data in a converted format that is suitable for the R/3 System.

You transfer a business object as follows:
Result
Your legacy data is transferred into the R/3 System.