Save and Save As
When saving a file for the first time, it doesn't matter if you choose to save it using Save or Save As. Both commands open the Save As dialog box.
After you save your work for the first time, you must continue to save in order to prevent lost work.
To do this, choose FileSave (Ctrl+S) or click the Save button. The Save As dialog box will not open again. To prevent lost work, always save before closing your file.
Save As lets you save an existing file under a new name, allowing you to create a new file. For example, let's suppose you intend to edit or revise a file but want to keep the original. Rather than start from scratch, use Save As to save it under a new name, then edit the new file while leaving the original untouched.