yeah! i strongly agree that if someone who knows the answer, he may share with us instead of just 'diving' here
Well, I would like to choose the simplest one as the very beginner
Q: what is LSMW?
A: The LSM Workbench is an SAP-based tool that supports You when transferring data from non-SAP systems ("Legacy Systems" to SAP systems once or periodically.
The tool supports conversion of data of the legacy system in a convenient way. The data can then be imported into the SAP system via batch input, direct input, BAPIs or IDocs.
Furthermore, the LSM Workbench provides a recording function that allows to generate a "data migration object" in an entry or change