I am using headers and footers in my document. I noticed that Word systematically adds an indent on the first line of every page, as though it were the beginning of a paragraph, and that indent is non-negotiable : if I try delete in that region the first words of the page move on to the preceding page.



I presume that this is not default behavior, and that I did something wrong somewhere. My guess is that the ident is there to add some spacing between the page number in the header and the first words of the page.

That is probably a result of not using "styles", or editing the style to fit your need. I consider "styles" to be the backbone of using Word. Here are some references that will help you:

Understanding styles | ShaunaKelly.com
Understanding Styles in Microsoft Word
Tips for Understanding Styles in Word | ShaunaKelly.com

Of course, there are many other links that will help you but these will get you started.

HTHs...