It is typically used:

• During initial SAP go-live to load historical data.
• For one-time or periodic data loads where manual entry is not feasible.
• When a business needs mass uploads/updates without custom ABAP programs.

The LSMW execution process follows 14 guided steps (though not all are mandatory):

1. Maintain Object Attributes – Define project, subproject, and object.
2. Maintain Source Structures – Define data hierarchy.
3. Maintain Source Fields – List legacy fields.
4. Maintain Structure Relations – Map source to SAP structures.
5. Maintain Field Mapping and Conversion Rules – Map fields.
6. Maintain Fixed Values, Translations, User Routines – Apply conversion logic.
7. Specify Files – Upload legacy file (CSV/TXT).
8. Assign Files – Link files to structures.
9. Read Data – Load file into LSMW.
10. Display Read Data – Verify uploaded values.
11. Convert Data – Apply mapping rules.
12. Display Converted Data – Check converted output.
13. Create Batch Input Session – Generate posting session.
14. Run Batch Input Session – Execute session and post data into SAP.

 In short: Use LSMW when migrating or mass-loading data into SAP. Process = Define → Map → Upload → Read → Convert → Post.