1-what are the types of saving of access file... another word what is the different between
Them?

2-how do you save an access file without change or modifying its contents?

Depends on the version. For version prior to Access 2007, the types that the user needed to be concerned with were MDB, MDE and MDW. The MDB file is the container for all Access objects. The MDE file is a compiled version of the MDB with much of the design elements locked. The MDW is the security file containing the settings for User Level Security (ULS).

With Access 2007, the type to be concerned with are ACCDB and ACCDE. Which are the equivalents of the MDB and MDE. Access 2007 doesn't support ULS.

Because an Access file is a container for all Access objects, those individual objects are saved during using a file. If you make changes to the data, then the tables are updated. If you change the design of a form, report, query, etc. Then when you close that object the changes can be saved.