I think it is called a gutter
Gutter
margin
It is called the header at the top of the page and a footer at the bottom of the page
A blank space around the edge of the pages.
margin
The blank space around the edges of a page is called the margin.
margin that is added to the top of the page
The space between a page's content and the edge of the page is called "margin" in printing, as well as web design.
Margin is the blank space at the top, bottom, left and right sides of the document or page.
As you look at the page, the distance between the edge of the paper on your right to the last character that is possible in the columwise in a particular line is called the right margin
The margin of error in the poll was 5%. The margin at the top of the page was 1.5 inches.
This is called the header and the one at the bottom is called the footer.