Would somebody be kind enough to correct my understanding of the following (if incorrect)? Microsoft's .mdf file-type can be used by both the LocalDB and the full Server database engines (apologies if engine is not the correct word?). The .mdf file does not care which of these two options are accessing it - so you could use either to access any given .mdf file, provided you had permissions and password etc. The LocalDB and the SQL Server are two options that can be interchangeably chosen to access .mdf files depending on the application requirements. Appreciate any clarification. Thanks