Saving your work is generally a very important part of working with a program. If you don't save your work, you might lose important data. With Access, it's also important to save your work, but you don't have to do it. Access automatically saves your work as you do it. You don't have to worry about losing your changes, but you do have to remember that any changes you make are permanent and can be undone by using the Undo button on the Database toolbar or Undo command on the Edit menu, or changing your data again. The Undo command provides multiple undos, where you can step back through your changes.
The Save button on the Database toolbar and the Save As command on the File menu allow you to save the design aspects of new or existing database objects, such as a table, query, form, or report, but not the data the object contains.
When Access saves a new database created in Access 2003, the default file format is Access 2000, which provides maximum compatibility with existing databases. If you want a different default file format, you can change it using the Options command on the Tools menu.