Normal.dotm is a template file on which all new blank documents loaded. Whenever you will start Microsoft Office Word 2016 it automatically open Normal.dot file first & includes default styles and customization’s that control the basic look of your document.Anytime you will make Changes to Normal.dotm file it will be applied then to documents that you will create in the future.
In previous versions of Word before Word 2007, the Normal template was known by the name normal.dot.
There are many ways to navigate to normal.dotm file location, but if you are in Word 2013, the easiest way is to click the File tab > Open > Computer > Browse.
If by any chance your normal.dotm files gets corrupted or shows any error, then to solve this error follow this link Normal.dotm Error in Word 2016 . If you will delete this file accidentally then next time when you will open Word it will look for the file, and when it can’t find it Word will recreate the file in its original default condition. So that means that the easiest way to reset all the changes you have made to the Normal template is to delete normal.dotm file. Note that the file cannot be deleted or modified if Word has other documents open.