Hello!
The missing word and the answer is header.
"Text repeated at the top of every page is called header."
Why?
A header or page header is a text or an image/text combination separated from the document body, used to show important information like page number, logos, author's information, titles, among others.
The opposite of a header is the page footer. Footers are commonly used to show information like page number.
Have a nice day!